US 2005O230659A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2005/0230659 A1 Hampden-Smith et al. (43) Pub. Date: Oct. 20, 2005
(54) PARTICULATE ABSORBENT MATERIALS Related U.S. Application Data AND METHODS FOR MAKING SAME (63) Continuation-in-part of application No. 10/723,424, (76) Inventors: Mark J. Hampden-Smith, filed on Nov. 26, 2003. Albuquerque, NM (US); Paolina Atanassova, Albuquerque, NM (US); (60) Provisional application No. 60/525,462, filed on Nov. Jian-Ping Shen, Albuquerque, NM 26, 2003. Provisional application No. 60/525,467, (US); James Brewster, Rio Rancho, filed on Nov. 26, 2003. NM (US); Paul Napolitano, Publication Classification Albuquerque, NM (US); Agathagelos Kyrlidis, Malden, MA (US) (51) Int. Cl." ...... C09K 3/00 (52) U.S. Cl...... 252/189 Correspondence Address: (57) ABSTRACT MARSH, FISCHMANN & BREYFOGLE LLP Solid absorbent materials that are useful for absorption of 3151 SOUTH WAUGHN WAY chemical Species from a fluid, Such as a gas Stream or a SUTE 411 liquid Stream. The absorbent materials are formed by Spray AURORA, CO 80014 (US) processing and posses a well-defined chemical composition and microstructure. The absorbent materials can have a high absorption capacity for a chemical Species Such as H2S, (21) Appl. No.: 10/996,672 CO, NO, and H and have a high recylability, such that the chemical Species can be absorbed and desorbed over a large (22) Filed: Nov. 24, 2004 number of cycles.
Increasing Temperature and Time old Liquid Phase Solid State
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6 &N N - Fig. 23 Patent Application Publication Oct. 20, 2005 Sheet 22 of 57 US 2005/0230659 A1 Carbonation: 600C Decarbonation: 750°C 45.0 40.0 35.0 -0- CaO1 30.0 (Prior Art) 25.O 2O.O 15.0 1 O.O 5.O 0.0 O 5OOO 1OOOO 15OOO 2OOOO Time (sec) Fig. 24 Patent Application Publication Oct. 20, 2005 Sheet 23 of 57 US 2005/0230659 A1 Á??oede.OZOO (e|duues600??OO6) [-]91,aloko ?,?8||313Ko T??ozepoko zze?oÁo Fig. 25 Patent Application Publication Oct. 20, 2005 Sheet 24 of 57 US 2005/0230659 A1 60 CaO1 (27 cycles) CaO1 (Prior Art) Avg. pore dia (nm) BET(m/g) Pore volume (x100 cc/g) CaO1 (Prior Art) CaO1 (27 cycles) Fig. 27 Patent Application Publication Oct. 20, 2005 Sheet 25 of 57 US 2005/0230659 A1 Z-Vy G-W S&SRSSSSSSSSSSSSSSSSSS&Ss 7-W is:sixxxxxx-xxxxxxxxxxxx& xxxx 9-V (JW Joud) OleO (WJOJ) ZOeo (iv Joud) OleO C. C C C C C C C C. 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O 80.0 S 60.0 5 7. s 40.0 y S; Ot 2O.O s O O.O i an O 5000 10000 15000 2OOOO Time(sec) Fig. 38 Patent Application Publication Oct. 20, 2005 Sheet 35 of 57 US 2005/0230659 A1 CaO-TiO2 (4:1 molar ratio) Carbonation 600C Decarbonation 800C C .9 5 CS t C .9 5 c CD O CVS O O.O sease O 5OOO 10000 15000 2OOOO Time(sec) Fig. 39 Patent Application Publication Oct. 20, 2005 Sheet 36 of 57 US 2005/0230659 A1 CN O s O r 9. C 9 e O (fff) uequoSce?zO3 "Aloedeo Patent Application Publication Oct. 20, 2005 Sheet 37 of 57 US 2005/0230659 A1 O O O O CN O O O D V s O O 55 v.N 35 : - O. Y 9E L O O O LO O C C C C C C C. O O. O. O. O. O. O. CN O OO CO. Y. 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Patent Application Publication Oct. 20, 2005 Sheet 52 of 57 US 2005/0230659 A1 ººººººçSS’OESN’çSS’OESS’OESS,OESS 9G-61-I | | || | |: | | çSS’OESS’OESS (edules f500/2006) Aboedeo ZOO Patent Application Publication Oct. 20, 2005 Sheet 53 of 57 US 2005/0230659 A1 ZG-61-I O009uO??euOqueO?p‘OuO??euOQJeO:GOL-VE !||º?º,, 070|| (%lou) uOpely uoloee Oeo Patent Application Publication Oct. 20, 2005 Sheet 55 of 57 US 2005/0230659 A1 %so % / Os (1 9. S2 70 (S) o (%lou) uO)3ely uo)3ee Oeo Patent Application Publication Oct. 20, 2005 Sheet 56 of 57 US 2005/0230659 A1 (edues foOIZOOf) Aboedeo ZOO Patent Application Publication Oct. 20, 2005 Sheet 57 of 57 US 2005/0230659 A1 (%lou) uo.3e UOBoee Oeo US 2005/0230659 A1 Oct. 20, 2005 PARTICULATE ABSORBENT MATERIALS AND to remove HS by wet scrubbing. However, this practice METHODS FOR MAKING SAME reduces the Overall efficiency of the power generation plant Significantly. Hot gas cleanup methods capable of operating CROSS REFERENCE TO RELATED at temperatures close to the gasifier outlet temperature, Such APPLICATIONS as from 725 C. to 1325 C., would increase the overall 0001. This application is a continuation-in-part applica energy conversion efficiency of the plant. While various tion of U.S. patent application Ser. No. 10/723,424, entitled absorbents have been proposed for desulfurizing hot coal “FUEL REFORMER CATALYST AND ABSORBENT gas, few are effective at Such high temperatures. MATERIALS", filed Nov. 26, 2003. This application also 0008. It is also known that zinc-based materials such as claims priority to U.S. Provisional Application No. 60/525, ZnO (zinc oxide) are highly effective for removing HS at 462, entitled “PARTICULATE ABSORBENT MATERI temperatures below about 650 C. Zinc-based compounds ALS AND METHODS FOR MAKING SAME, filed Nov. can be combined with other metal oxides (such as Al-O or 26, 2003, and to U.S. Provisional Application No. 60/525, TiO) to prepare absorbent materials with enhanced perfor 467, entitled “CARBON DIOXIDE ABSORBENT MATE mance. U.S. Pat. No. 4.313,820 to Farha et al. describes the RIALS AND METHODS FOR MAKING SAME, filed combination of Zinc oxide with titania and at least one Nov. 26, 2003. This application is also related to U.S. patent promoter Selected from Vanadium, chromium, manganese, application Ser. No. , entitled “FUEL REFORMER iron, cobalt, nickel, molybdenum, rhenium and their com CATALYST AND ABSORBENT MATERIALS, filed on pounds. U.S. Pat. No. 6,479,429 to Khare discloses a sorbent Nov. 24, 2004, and further identified by Attorney File No. prepared by mixing a zinc-containing compound with an 41890-01736. Each of the foregoing applications is incor alumina component, among other components, Spray drying porated herein by reference in its entirety. the mixture to form particles and then Subsequently calcin ing the mixture to form an enhanced HS sorbent. Other BACKGROUND OF THE INVENTION combinations of metal oxides with Zinc oxide are also known in the art, Such as combinations with oxides of iron 0002) 1. Field of the Invention and/or nickel, Such as those described in U.S. Pat. No. 0003. The present invention relates to solid particulate 5,244,641 to Khare. In certain cases, mixed oxides are materials that are useful for the reversible absorption of prepared with the addition of an activator, Such as a noble chemical Species from a fluid, Such as from a liquid or metal oxide, copper metal, copper carbonate, and others, to gaseous stream, and particularly the removal of gases Such enhance the kinetics of the adsorption process. This process as CO, HS or NO, from a gas stream. Particulate mate is described in U.S. Pat. No. 6,251,348 to Scranton. U.S. Pat. rials useful for the reversible absorption of hydrogen are also No. 4,729,889 to Flytzani-Stephanopoulos et al. describe provided. The particulate absorbent materials can be pro regenerable HS Sorbents consisting of mixed oxides of duced by Spray processing to form a powder batch of Group VB or VIB metals and Group IB, IIB, VII metals absorbent material particulates, or intermediate compounds Supported on refractory metal oxide Supports, Such as alu that can be converted to the absorbent material. The absor mina or zirconia. Similarly, U.S. Pat. No. 4,489,047 to de bent material particulates can be fabricated into shapes. Such Jong et al. describes the use of MnO, or iron oxide, Sup as extrudates, pellets or monoliths. ported on a porous carrier consisting of alumina, which may also contain silica. U.S. Pat. No. 4,089,809 to Farrior et al. 0004 2. Description of the Related Art describes the use of Silica Supported iron oxide for the 0005 Solid absorbents are utilized in a wide range of removal of HS from gas Streams. The contents of each of applications to remove a chemical Species from a gas or the foregoing U.S. patents are incorporated herein by refer liquid Stream. There are Several mechanisms by which ence in its entirety. absorbents can remove the targeted chemical Species, including physical Sorption, chemical Sorption and chemical 0009. At higher temperatures, calcium-based absorbents reaction. The first two categories rely on the Surface area and are promising because the reaction of CaO with HS is both the surface composition of the solid sorbent to react with the thermodynamically and kinetically favorable. These reac targeted Species and remove it from the Stream. Solid tions are illustrated by Equations 1 to 4. reactive absorbents are chemical compounds that fix the Absorption: CaO +HS->CaS+HO (1) Selected chemical Species by reacting with the chemical Species to form a new compound. Oxidation: CaS+2O->CaSO (2) Reduction: CaSO+CO->CaO+CO+SO, (3) 0006. Applications of these absorbent materials include, but are not limited to, the treatment of fuels to purify the CaSO+H->CaO +HO--SO, (4) fuels and the treatment of combustion gases, Such as from a 0010. It has been proven by van der Ham et al. (Ind. Eng. coal-fired power plant or an internal combustion engine, to Chem. Res., 1996, 35, 1487) that the HS content of gas remove noxious components. The removal of HS (hydro produced by an air- and Steam-blown coal gasifier operating gen Sulfide) is motivated primarily by the desire to reduce under typical conditions can be reduced to 20 ppmV by environmental pollution. Also, the removal of Sulfur-con employing CaO in highly reducing conditions at a tempera taining species, even to below the trace (ppm) concentration ture higher than 800° C. Regeneration can be accomplished range, is desired prior to the use of gases in other applica at a temperature above the absorption temperature by tions, as Sulfur can poison various catalysts. employing a cyclic oxidation and reduction process as is 0007 Generally, coal includes Sulfur as an impurity, disclosed in U.S. Pat. No. 6,083,862 to Wheelock. which upon gasification typically enters the coal gas Stream 0011 CO (carbon dioxide) is another chemical species as HS. It is common practice to cool the gas below 77 C. that is often removed from certain fluid streams. Several US 2005/0230659 A1 Oct. 20, 2005 technologies and processes are currently available to Sepa 0017 Reactive absorbent compounds are chemical com rate and capture CO2 from other gases. Separation and pounds that fiX a Selected chemical Species by reacting with capture is often required to: (1) remove CO2 that is either the chemical Species to form a new compound. An example present or produced as a co-product or by-product in indus is the reaction of a metal oxide (M.O.) with CO to form a trial processes, Such as Synthetic ammonia production, H. carbonated compound (MCO), as is illustrated by Equa production and natural gas processing; and (2) prevent the tion 5 for calcium oxide and Equation 6 for lithium oxide: atmospheric release of CO2 when it is created during the generation of electricity, Such as by coal combustion. CaO+CO->CaCO (5) LiO--CO->LiCOs (6) 0012. With regard to the removal of CO in industrial processes, pressure Swing adsorption (PSA) is a common 0018. In many applications, it is desirable after absorp commercial process, and utilizes pressure changes to pro tion to regenerate the absorbent by desorbing the CO from mote the cyclic adsorption and desorption of the gas. Gen the carbonate compound. This can be accomplished, for erally, a column packed with a highly porous reversible example, by heating the carbonate compound. adsorbent, Such as activated carbon or Surface modified 0019. A variety of reactive absorbent compounds are Zeolites is employed. available for the absorption of CO, and each has a different 0013. Other materials and methods used to remove CO absorption capacity. Chemically reactive CO2 absorbent are described by Wong and Bioletti in “Carbon Dioxide compounds are preferred, because these compounds typi Separation Technologies”, Alberta Research Council, the cally have much higher equilibrium absorption capacity than contents of which are incorporated herein by reference in other absorbents, as is illustrated in Table 1. their entirety. These materials and methods include physical Solutions, cryogenic Separation, membrane Separation and TABLE 1. chemical absorption. Absorption Capacity 0.014) Zeolite-based materials have been used for CO (grams CO2 per 100 removal in a variety of applications. For example, NH Material grams material) type or H-type faujasites, and ion-exchanged-type faujas methylethanolamine 6 (MEA) ites, Such as with Zinc or a rare earth can be used for CO silica gel 1.32 removal from a mixed gas of hydrogen, nitrogen and meth activated carbon 8.8 ane in the temperature range of 50 to 100 C., as described KCO/Hydrotalcite 1.98 in U.S. Pat. No. 4,775,396 to Rastelli et al., the contents of (HTC) which are incorporated herein by reference in their entirety. CaO 78.57 X or LSX ion-exchanged Zeolites can also be used for cryogenic purification of inert gas from CO2 to less than 10 ppb. These types of materials can also be used for hydrogen 0020. In general, alkali metal and alkaline earth metal purification by removal of CO from the reformate through oxides and/or hydroxides are good materials for CO Sorp PSA methods. Also, modified Zeolites, such as a zeolite tion. Reaction of CO with various metal oxides leads to the impregnated with one or more metal Salts can be used for formation of the corresponding carbonates, as described by hydrogen production from Steam reforming carbon-based the following equations: fuels, as is described in U.S. Pat. No. 6,565,627 to Golden et al., the contents of which are incorporated herein by reference in their entirety. 0.015 Similar to porous zeolites, support materials with high Surface area Such as alumina or activated alumina, are 0021. Such reactive absorbent compounds can be free also known to remove CO. For example, activated alumina Standing, mixed with or Supported on inert porous Sub with a high Surface area that contains at least 80% alumina Strates, Such as Silica (SiO2), alumina (AlO4), carbon, and oxide, silicon oxide, iron oxides and up to 7.25% of alkali the like. Known absorbent materials include calcium-based or alkaline-earth metal can be used for removal of CO from compounds, Such as calcium hydroxide (Ca(OH)) and air prior to cryogenic Separation or from a synthesis gas, as calcium oxide (CaO), magnesium-based compounds, Such disclosed in U.S. Pat. No. 6,379,430 to Monereau, the as magnesium hydroxide (Mg(OH)2) and magnesium oxide contents of which are incorporated herein by reference in MgO, and lithium-based compounds Such as lithium their entirety. The combination of activated alumina with hydroxide Li(OH) and lithium oxide LiO. These absorbents Zeolites can be used for CO2 removal for Semiconductor can be enhanced for certain applications with the addition of purposes. alkali metal carbonates (MCO, where M is an alkali metal) 0016 Other similar materials include aminated carbon or bicarbonates (MHCO, wherein M is an alkali metal), at molecular sieves, Such as those described in U.S. Pat. No. various stoichiometries, as described in U.S. Pat. No. 6,280, 4,810,266 to Zinnen et al., the contents of which are incor 503 to Mayorga et al., the contents of which are incorporated porated herein by reference in their entirety. Another class of herein by reference in their entirety. In other applications, materials are the Surface functionalized carbonaceous absor Such as the removal of CO2 from air for anesthesiology bents described in U.S. Patent Application Publication No. applications, the presence of alkali metal hydroxides can be 2002/0056686 to Kyrlidis et al., the contents of which are detrimental. For these applications, the absorbents should be incorporated herein by reference in their entirety, wherein alkali free, as described in U.S. Pat. No. 6,228,150 to the organic group attached to the Surface of the particle Armstrong et al., the contents of which are incorporated comprises one or more amines. herein by reference in their entirety. US 2005/0230659 A1 Oct. 20, 2005 0022. Other materials that have been used for the sorption emissions into the atmosphere and CO2 emissions from of CO include mixtures of metal oxides, alkali carbonates direct combustion of fossil fuels account for one-half of the and alkali fluorides, Such as those described in U.S. Pat. No. greenhouse effect that causes global warming. It is therefore 5,214,019 to Nalette et al., the contents of which are desirable to develop cost-effective CO management incorporated herein by reference in their entirety. Nalette et Schemes to curb CO2 emissions. Many CO management al. disclose that the metal oxide may be selected from the Schemes consist of three parts: Separation, transportation, group consisting of MgO, AgO, ZnO and mixtures thereof and sequestration. The capture of CO accounts for about and that these absorbents can be freestanding, mixed with or 75% of the total cost of CO management, and imposes a Supported on an inert porous Support. Similar mixed metal Severe energy requirement on fossil fuel-based power plants, oxide absorbents are described in U.S. Pat. No. 5,186,727 to reducing their net electricity output by as much as 37%. The Chang the contents of which are incorporated herein by costs associated with current CO2 Separation technologies reference in their entirety. These mixed metal oxide absor necessitate the development of economical alternatives. It is bents consist of mixtures of a salt of silver metal with a salt believed that, none of the preceding materials and methods of a Second metal Selected from magnesium, iron, cobalt, have been applied at the Scale required for a commercial nickel, Zinc and other metals for which the carbonate to CO, emissions mitigation strategy that also meets the asso oxide reaction is reversible. Chang discloses that the pre ciated cost and Safety requirements. AS Such, techniques are ferred metal Salt is the carbonate or bicarbonate Salt. needed to transform absorbed CO2 materials into materials 0023 Iron oxide based absorbents for the absorption of that can be economically and Safely disposed, can be trans CO, are also known in the art. Such materials have applica ported and Sequestered for a long time, or can be used to tions in the food industry, Such as in the packaging of coffee make commercial products that can offset the associated and/or the removal of CO2 from containers that hold respir costs of capture and transport. One potential Solution is the ing fruits and vegetables, as described by Brody et al. in carbonation of Silicate rock, where CO2 is captured in a “Active Packaging for Food Applications”, CRC Press, the stable and solid form for disposal. Preliminary estimates for contents of which. are incorporated herein by reference in Silicate carbonation are in development, but show the poten their entirety. Solid CO absorbents can also be combined tial for a significantly lower cost than Solvent extraction. with noble metal oxidation catalysts for the removal of trace 0026. In addition to the above, several smaller-scale amounts of CO and H from gas streams by concurrent applications exist for the removal of CO. Specifically, Small oxidation and sorption, as described in U.S. Pat. No. 6,589, Scale applications exist for enclosed environments, whose 493 to Hosaka et al. and U.S. Pat. No. 6,113,869 to Jain et elevated concentrations of CO2 are potentially dangerous, al, the contents of each being incorporated herein by refer Such as Submarines, Space Systems, anesthesia machines and ence in their entirety. diving rebreather equipment. CO absorbents can also be 0024. Another class of sorption materials effective for used in the removal of trace concentrations of CO2 from air CO, removal for both synthesis gas and effluents are porous, prior to cryogenic Separation applications, or removal of Solid materials Such as mixed oxides of lithium and Silicon acid gases for the preparation of ultra-pure inert gases for and/or Zirconium. For example lithium zirconate (e.g., Semiconductor and other high purity applications. CO2 LiZrO) and lithium silicates (having the general formula absorbents are also used as components of CO. Sensors due LiSiO) as is described in U.S. Pat. No. 6,387.845 by to the change in their physical properties as they absorb Masahiro et al., the contents of which are incorporated CO. In addition, CO absorbents can help remove CO from herein by reference in its entirety, are examples of Such Sensors of other gases, when the adsorption of CO2 interferes materials. It is disclosed that these materials can also incor with the Sensing of the other target gas. In general, CO porate other dopants to enhance their performance, Such as absorbents can be utilized in any application where it is Al, K, Fe, Mg, and the like, and that the lithium-based important to control the presence, concentration or release of materials are reversible upon the application of heat. While CO2, and includes chemical applications and applications the use of lithium Zirconate is more widespread at present, related to cell culture and/or fermentation processes. the adoption of lithium Silicate is increasing due to its lower production costs, lighter weight and rapid CO2 absorption 0027 Natural CaO-based absorbents for the absorption of H2S and CO2, Such as limestone and dolomite, are capabilities. For example, one gram of lithium Silicate is plentiful and inexpensive, but they are Soft, friable and do capable of absorbing 62 milligrams of CO, making the not Stand up well to handling and use for multiple cycling. material 30 times more efficient than lithium zirconate. To improve- the recyclability, Some work has focused on the Lithium silicate is also 70 percent lighter and about 85 pelletizing of limestone by using different binders. Work percent less expensive than lithium Zirconate, Since it uses also focused on the modification of natural materials, Such Silicon instead of the more expensive Zirconium as a starting as dolomite, to tailor the physicochemical properties of the material. material. The synthesis of a CaO-based absorbent by boiling 0.025 Despite the breadth of existing and potential solu of CaO into Ca(OH) or the carbonation of calcium salt tions for the Separation and capture of CO, there is still the Solution Such as calcium nitrate or Ca(OH) into calcium need for improvements in the areas of capacity, high carbonate, and Subsequent decomposition of the carbonate temperature operation and long-term Stability. Indeed, the into CaO is disclosed by L. S. Fan et al., Ind. Eng. Chem. need for Such absorbents is even more pronounced with Res., 1999, 38,2283. Others have disclosed the preparation regard to the removal or collection of CO2 present in the flue of CaO-based materials by aerogel methods. Other various gases of fossil-fueled power plants, chemical plants and materials useful for the absorption of HS are disclosed in engines, the presence of which is a contributing factor in U.S. Pat. No. 4,729,889 to Flytani-Stephanopoulos et al., the global warming and ocean acidification. The increasing use contents of which are incorporated herein by reference in of fossil fuels to meet energy needs has led to higher CO2 their entirety. US 2005/0230659 A1 Oct. 20, 2005 0028 Generally, the above described methods result in from gas mixtures, if they interfere with the performance of poor control over the composition and microStructure of the the Sensing material for the other components of the gas powders. The morphology and Surface properties Such as mixture. Surface area, pore Volume and pore size, are characteristics that impact the performance of the absorbent. This is pri 0034. The abatement of NO can be achieved using marily due to the nature of the reactions that occur. With various methods, (see for example EPA Technical Bulletin respect to CO2, carbonation takes place on the external and 456/F-99-006R), some of which interfere with known internal Surfaces of the CaO-based absorbent, thereby form mechanism of NO production, and others which help with ing a carbonate layer. AS the chemical reaction advances, the abatement of the NO species after they are formed. CO, diffuses through the carbonate layer into the unreacted 0035) A variety of materials have been developed over core CaO active Sites. Therefore, higher reactivity and faster the years for the absorption of nitrogen oxides. The com kinetics can be expected for Small particle Size CaO due to position and performance of these materials is Strongly a the higher ratio of atoms on the Surface. A more porous function of the conditions under which they are expected to Structure will also lead to higher reactivity and recyclability, act as absorbents. Each material performs best in a specific and a lower decarbonation temperature due to the easier CO2 environment. In Some applications Selection of a NO absor diffusion into and out of the outer carbonate layer. bents is a function of its regenerability. An additional factor 0029 Absorbent materials that can reversibly absorb is the, potential for combining these materials with a catalyst and/or Store NO (nitrogen oxides) are also known. The for reducing the nitrogen oxides to inert nitrogen. Huang and emission of NO (e.g., NO, NO, etc.) is detrimental to the Yang (Langmuir, Vol. 17, (2001), pp. 4997-5003) and its environment. It has been shown that NO, can lead to the references list a variety of these materials, the contents of production of pollutants, Such as OZone and can also lead to each being incorporated herein by reference in their entirety. the formation of acid rain. One primary application for NO 0036 Alkali metal, alkaline earth, or lanthanide oxides, Sorbent materials is the removal of nitrogen oxides from hydroxides, and/or carbonates can trap nitrogen oxides exhaust gases. Exhaust gases generally are the products of through the mechanism: the combustion of automotive fuels, e.g., long-chained hydrocarbons. The EPA estimates that 50% of NO emis Sions are from mobile Sources (e.g. automobiles) and about 30% are from Stationary Sources (e.g. electric power plants). Preferably, NO, is removed at the place of generation (in the 0037) The metal (M) can be selected depending on fac vicinity of the engine) or from enclosed spaces, Such as torS Such as cost, desired capacity, and operating conditions. tunnels, garages, or other enclosed Structures, where the Typical metals include Sodium, potassium, calcium and gases may accumulate over time. barium. Such materials may be used alone or in combination 0030 There are several other applications that would with an inert Support, Such as alumina, Silica, as described benefit from NO absorption, including pickling operations for example in U.S. Pat. No. 4,755,499 to Neal et al., the in Steel mills and Silicon processing. In addition, chemical contents of which are incorporated herein by reference in plants that produce nitric acid or that utilize nitric, or nitrous their entirety. Such inert materials may provide a Substrate acids as reagents are additional Sources of NO emissions with the desired porosity, pore size distribution, and Surface that could benefit from NO absorbents. NO present in air area to Support the active Sorbent. can also interfere with the cryogenic Separation of oxygen 0038) Other materials that have been found to have and nitrogen and the manufacture of ultrapure gases for enhanced Sorption capacity for NO are mixed oxides of Specialty applications (i.e. Semiconductor processing) as manganese (MnO) and Zirconium (ZrO2) (as described by described in U.S. Pat. No. 6,358,302 to Deng et al., the Eguchi et al., J. Catal. Vol. 158, (1996), p. 420, the contents contents of which are incorporated herein by reference in of which are incorporated herein by reference in their their entirety. entirety). The performance of these mixed oxides can be 0.031 Nitrogen oxides are also used in combination with enhanced by the incorporation of additional metal oxides, oxygen and anesthetics in various medical applications, Such Such as oxides of titanium and/or iron. as laughing gas. It is important in these applications to 0039 Compositions including Y-Ba-Cu-O mixed controllably release Such gases during the anesthesia and to oxides have also been shown to have is enhanced Storage capture any fugitive gases. capacity for nitrogen oxides. For example, U.S. Pat. No. 6,379,432 to Matacotta et al., the contents of which are 0.032 Nitrogen oxides can also interfere with the opera incorporated herein by reference in their entirety, describes tion of a variety of devices. For example, copying machines, a BaCuO Sorbent whose activity can be enhanced with the Such as those described in U.S. Pat. No. 5,539,205 to Reale, incorporation of oxides of La and/or Ce. Arai et al., Catalysis can generate nitrogen oxides that need to be abated in order Today, Vol. 22 (1994), pp. 97-109, disclose the sorption of to maintain reliable performance during operation of the nitrogen oxides on YBa-Cu-O, which has been shown to device. Printed circuit boards, hard drives, or other computer have good Sorption capacity for NO. These materials can hardware components that are operated in harsh environ also be Supported on inert porous Supports, Such as those ments containing acid gases, Such as nitrogen oxides, can described above. Copper oxides Supported on titanium diox also Suffer Significant deterioration in performance in the ide and copper oxides Supported on titanium dioxide, which presence of NO. incorporates cerium oxides, have also been shown to have 0033. An additional application for NO absorbent mate enhanced performance by Lietal. (Energy & Fuels, Vol. 11, rials is in the area of Sensors. The performance of Sensors for (1997) pp. 428-432), the contents of which are incorporated other gases can be enhanced by removing nitrogen oxides herein by reference. US 2005/0230659 A1 Oct. 20, 2005 0040. The beneficial effect of cerium dioxide for the often referred to as a misch metal hydride. Typical misch Sorption of nitrogen oxides is also described by Haneda et al. metal compositions include AB, AB, AB, ABs and AB, (Phys. Chem. Chem. Phys., vol. 3, (2001), pp. 4696-4700), where A can be selected from lanthanide elements (e.g., La, the contents of which are incorporated herein by reference in Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Th, Yb and Lu) their entirety. It is disclosed that the performance of a as well as Mg, Ti and Zr, and B can be selected from the CeO:ZrO mixed oxide prepared by Sol-gel processing was transition elements (e.g., Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, found to be significantly better than that of a similar material Zn, Y, Zr, Nb, Mo, Rh, Ru, Pd, Ag, Cd, La, Ce and the like). prepared by a co-precipitation method. See Zuttel, Materials Today, September 2003, pp. 24-33, 0041. Other materials that have been shown to Sorb which is incorporated herein by reference in its entirety. nitrogen oxides include amino acid and amine impregnated Preferred examples of such materials include LaNis, Mg-Ni, porous carriers, such as those described in U.S. Pat. No. Mg,Fe, TiFe, and ZrMn. For example, LaNis forms a 6,171,372 to Ichiki et al., the contents of which are incor Species with the empirical formula LaNishes and is the porated herein by reference in their entirety. Microporous material of choice for nickel/metal-hydride batteries. Other carbons modified by FeO have also been shown by Inai et examples are given in G. Sandrock, Journal of Alloys and al., (Catal. Lett., Vol. 20 (1993), pp. 133-139) to absorb NO Compounds 293-295 (1999) 877-888, which is incorporated from mixtures. Microporous carriers with dispersed nano herein by reference in its entirety. These materials have very particles that have affinity towards nitrogen oxides can reliable reversible hydrogen uptake and are currently in use enhance the capacity for adsorption of Such materials. in nickel-metal hydride batteries. These materials are also Alkali, alkaline earth, rare earth and transition metal cation commonly used for hydrogen Storage, but have a low eXchanged Zeolites have also been explored as nitrogen gravimetric hydrogen capacity, between 1 and 3 wt.%. In oxide Sorbent materials. Other materials that have been addition, these materials typically decrepitate after the first evaluated include perovskites (ABO, where A=Ca, Sr., Ba adsorption/desorption cycle to form a powder that is pyro and B=Sn, Zr, Ti), including BaSnO. phoric when exposed to air. 0.042 Absorbent materials can have multi-functional 0046) Another class of hydrogen storage material is components. For example, Several of the mixed metal oxides referred to as chemical hydrides. Chemical hydrides are listed above have components with very Specific functions: Stoichiometric chemical compounds, typically molecular or a component that helps oxidize NO to NO and a component oligomeric, but which can Stoichiometrically, reversibly that Stores the nitrogen oxides either on its Surface or in its react with, or release, H2. In order to achieve a Suitable bulk by reaction to the corresponding metal nitrate. Such gravimetric H. Storage capacity, these materials usually absorbent materials can also be used as Supports for noble include hydrides of lighter elements, Such as Mg, B, Al, Li, metal catalysts that catalyze the oxidation of NO to NO, and Na, or complexes thereof, including NaBH, AlH, LiAlH, reduce of absorbed nitrogen oxides to nitrogen. Supporting Mg(AlH). These materials generally have H Storage a noble metal catalyst on the Sorbent material can Signifi capacities of up to 9 wt.%. For example, NaAlH reversibly cantly enhance the kinetics and overall conversion of the reacts to form 1/3 NaAlH+2/3 Al-H, which can further reversibly react to form NaH+A1+3/2H. The theoretical NO, reduction reaction. hydrogen Storage capacity for this reaction is about 5.6 wt. 0.043 All of the materials described above expand their %. Another promising material is LiBH, which has a Volume upon absorption of NO, during the Sorption process. relatively high gravimetric hydrogen density (s18 wt.%), as The molar volumes of the nitrates are higher than those of the Starting oxides, carbonates, or hydroxides, leading to a described by Zuttel, Supra. weakening of the materials during the Sorption process, as 0047. In the same class as chemical hydrides are some they expand. After a few regeneration cycles Such materials Specific metal hydride compositions which form a known will become brittle, and, possibly, crumble into finer par alloy phase on loss of H. An example of Such as compound ticles or fall off the Support Structures. Smaller particles can is Mg2NiH, which forms 2H and Mg2Ni alloy. Another clog pores, Sinter, and/or have significant negative effects on example is Mg2FeH, which has the potential for 5.5 wt.% the Sorption capacity and kinetics after Several cycles. For H Storage. materials that absorb nitrogen oxides into their molecular 0048. In general, it is believed that the addition of Structure, as well as for materials that adsorb nitrogen oxide dopants or catalysts can enhance the Storage capacity, kinet molecules on their Surface, it is important to maintain ics, and regenerability of most chemical hydrides. For absorbent capacity throughout the use of the Sorbent mate example, in the case of complex metal hydrides, the addition rial. Thus, absorbent powders need to be able to maintain of a Ticatalyst to sodium alanate (NaAlH) as described by their pore Structure and Surface area even after repeated Bogdanovic and Sandrock (MRS Bulletin, September 2002, absorption and desorption cycles. pp. 712-716), leads to an increased reversible capacity at 0044) Certain absorbent materials can also reversibly 150 C. In the case of simple metal hydrides, the incorpo Store H (hydrogen). He storage materials are normally ration of NbOs and other metal oxides into Mg can have a categorized into three different classes according to their Significant effect on the adsorption and desorption kinetics composition and the mechanism for hydrogen storage (e.g., of MgH. See Barkhordian et al., (Scripta Materialia, 49, chemisorption or physisorption). Each class of materials has (2003), pp. 213-217). unique properties in terms of the environment in which 0049 Other materials that can-store hydrogen are alkali hydrogen adsorption and desorption occurs, which in turn metal nitrides and imides, especially lithium-based com determines the operating range and possible applications for pounds such as LiN. See Chen et al. (Nature, 420, (2002), the hydrogen absorbent. pp. 302-303). 0.045 One type of hydrogen storage material is a metal 0050 A third class of hydrogen storage materials are alloy or intermetallic compound that includes a misch metal, those that physisorb hydrogen, which are typically highly US 2005/0230659 A1 Oct. 20, 2005 microporous nanostructured materials. A range of Such 0053. There are also other types of materials, which have materials is described by Nijkamp et al. (Applied Physics A, been demonstrated to exhibit hydrogen Storage properties. 72, (2001), pp. 619-623), the contents of which are incor These include a number of carboxylate compounds Such as porated herein by reference in their entirety. These materials Zinc acetate. are usually inorganic carbon, Silica or alumina based mate 0054 There are several aspects to the design of hydrogen rials with high pore Volumes, Such as activated carbons, Storage materials which must be Successfully addressed in Zeolites and others. Organic/metalorganic materials tailored order for Such materials to be commercially viable. First, nanostructures, are also known. Such materials must have a reasonable reversible hydrogen Storage capacity. The US DOE target for automotive appli 0051. The most promising hydrogen absorbing materials cations is currently 6.5 wt.% reversible hydrogen Storage. include carbon particles and carbon nanotubes/fullerenes. Second, the hydrogen Storage materials must also exhibit a These materials may also include hetero atoms which reproducible capacity over many cycles of hydrogen uptake enhance the hydrogen uptake. Such carbon-based materials under conditions of temperature and preSSure, which are can also have Surface functionalization groups that enhance preferably close to room temperature and pressure. Further, the capacities and kinetics of hydrogen Storage. High Surface the materials must also have good low-temperature kinetics area active carbons are known to physisorb molecular and equilibrium plateau preSSures. They must perform well hydrogen, but only at low temperatures due to the weak and be reversible under the highly exothermic charging Steps nature of the physisorption interaction. Conversely, chemi and must be incorporated in Systems with good thermal cal reaction of hydrogen with carbon (chemisorption) in the management. In addition, like most Sorbents, materials that form of fullerenes to form hydrocarbons, e.g., C.His chemically Store hydrogen expand during the adsorption results in the formation of covalently bonded hydrogen that Step, and become embrittled. Ideally, the materials should requires high temperatures to desorb the hydrogen. To remain intact during the course of the reversible hydrogen resolve this dichotomy, a number of solutions have been uptake and avoid decrepitation, which can have Serious explored. A reduction in the chemical Stability of the carbon operational and Safety issues. materials may bring the adsorption/desorption kinetics 0055. It would be advantageous to provide a method for closer to room temperature. Also, Single wall carbon nano producing particulate absorbent materials or intermediate tubes have dimensions that are close to that required for compounds capable of being converted to absorbent mate capillary condensation of hydrogen molecules and may offer rials that would enable control over the powder character an alternative Strategy. Finally, the incorporation of metal istics Such as particle size, Surface area and pore Structure, particles into the Structure of the carbon particles may as well as the versatility to accommodate compositions provide another mechanism to bring the reaction conditions which are either difficult or impossible to produce using closer to more commercially viable conditions. A recent existing production methods. It would be particularly advan example of such materials is described in U.S. Patent tageous if Such powders could be produced in large quan Application Publication No. 2002/0096048 by Cooper et al., tities on a Substantially continuous basis. Further value can which is incorporated herein by reference in its entirety. be derived from these powders if they can be incorporated into Structures that can be integrated into reactor beds that 0.052 Reversible hydrogen storage materials also include enable a Suitable combination of high Space Velocity and metals, Such as Pt, or metal alloys, mixed with or dispersed high absorption capacity while retaining their performance on the Surface of carbon particulates. The carbon particles characteristics. Such structures include coatings Such as may also be modified on their Surface with organic func wash coatings on highly porous monoliths, pellets that have tional groups to enhance their absorption capability in a pore Structures that retain the performance of the powders, number of different ways. Surface. modification helps to and also coatings or impregnation of the powder particles Selectively bind a catalytically active material, Such as a into other Structures, Such as metal cloths which provide molecular metal-containing complex or a nanometer-sized beneficial heat transfer characteristics. catalytically active particle, to the Surface of the carbon SUMMARY OF THE INVENTION particle. Modified carbon blacks comprising metal particles 0056. The present invention is directed to reversible are described in U.S. Pat. No. 6,399,202, U.S. Pat. No. absorbents that have high absorption capacities and can 6,280.871, U.S. Pat. No. 6,630,268, U.S. Pat. No. 6,522,522, withstand many regeneration cycles without significant loSS U.S. Patent Application Publication No. 2003/0017379 and of performance. U.S. Patent Application Publication No. 2003/0022055, each of which is incorporated herein by reference in its 0057 According to one embodiment of the present inven entirety. Surface functional groups also affect the uptake of tion, a particulate absorbent material for the absorption of a gaseous Species, Such as hydrogen, by changing the packing chemical species from a fluid (e.g., a gas or a liquid) is characteristics of the carbon particles, as well as the carbon provided. The absorbent material is fabricated by a process Surface characteristics to be, for example, hydrophobic or including the Steps of providing a precursor Solution com hydrophilic. Typical Surface function groups include car prising at least a first precursor to an absorbent compound, boxylic acids, Sulfonyllic acids, amines and the like. A atomizing the precursor Solution to form precursor droplets method by which the surface of the carbon particles can be comprising the first precursor, heating the precursor droplets modified is through reactions with diazonium Salts of the remove liquid therefrom and form dried precursor droplets desired organic functional groups, as described by Belmont and converting the dried precursor droplets to a particulate et al. in U.S. Pat. Nos. 5,851,280, 6,494.946, 6,042,643, absorbent material. 5,900,029, 5,554,739 and 5,672,198, each of which is incor 0058 According to one aspect of this embodiment of the porated herein by reference in its entirety. invention, the heating Step and the converting Step occur US 2005/0230659 A1 Oct. 20, 2005 Sequentially in a Spray pyrolysis. According to another 0067. According to another aspect, the particulate absor aspect, the heating Step forms an intermediate compound bent material is further heated in a post-processing Step. capable of being post-processed to form a particulate absor bent material, and the converting Step comprises heating the 0068 According to another aspect, the particulate absor intermediate compound to form the particulate absorbent bent material has a pore volume of at least about 0.04 g/cm, material. According to another aspect, the first precursor is Such as at least about 0.15 g/cm. According to another Selected from the group consisting of a metal nitrate, a metal aspect, the particulate absorbent material has a Surface area acetate, a metal oxalate and a metal hydroxide. According to of at least about 15 m/g, such as at least about 30 m/g. another aspect, the first precursor comprises a metal oxalate. 0069. According to another aspect, the absorbent material According to another aspect, the absorbent material com is adapted to absorb CO2 and has an absorption capacity of prises a metal oxide. According to another aspect, the at least about 20 grams CO2 per 100 grams of unreacted absorbent material comprises a metal oxide Selected from absorbent material. According to another aspect, the absor Group 1 and Group 2 metal oxides. According to another bent compound maintains the absorption capacity over at aspect, the absorbent material comprises a metal oxide least 100 cycles. According to another aspect, the absorbent Selected from the group consisting of magnesium oxide, material is adapted to absorb CO2 and has an absorption calcium oxide, Strontium oxide and barium oxide. According capacity of at least about 30 grams CO2 per 100 grams of to another aspect, the absorbent material comprises calcium unreacted absorbent material. According to another aspect, oxide. the absorbent material comprises an absorbent compound 0059. According to another aspect, the absorbent material having an absorption capacity of at least about 70 mol. 76. comprises a metal oxide and the precursor Solution com According to another aspect, the absorbent material com prises a metal Salt Selected from the group consisting of a prises an absorbent compound having an absorption capacity metal oxalate Salt and a metal hydroxide Salt. According to of at least about 90 mol. %. The absorbent compound can another aspect, the absorbent material comprises a misch maintain the absorption capacity over at least 100 cycles. metal. According to another aspect, the heating Step com 0070 According to one aspect, the heating step com prises heating the droplet in the presence of an oxygen prises heating the droplets in a spray dryer, Such as to form containing gas. According to another aspect, the precursor an intermediate compound that can be converted to an Solution further comprises a morphology-enhancing agent. absorbent material. 0060 According to another aspect, the precursor solution 0071 According to another embodiment, particulate also includes a morphology-enhancing agent Selected from absorbent material adapted for the absorption of a chemical the group consisting of lactic acid, glycine, alcohols, ammo Species from a fluid, the particulate absorbent material nium nitrate, polymers and carbohydrazide. comprises an intimate mixture of at least a first absorbent 0061 According to another aspect, the precursor Solution compound and a metal oxide that is different than the first further comprises a precursor to a compound Selected from absorbent compound, and the particulate absorbent material the group consisting of aluminum oxide, magnesium oxide, has a Surface area of at least about 5 m/g. Silicon oxide and titanium oxide. According to another 0072 According to another aspect, the absorbent com aspect, the particulate absorbent material comprises pound is Selected from Group 1 and Group 2 metal oxides. CaO:MgO. According to another aspect, the precursor Solu According to another aspect, the absorbent compound is a tion further comprises a precursor to magnesium oxide, Such calcium compound, Such as CaO. According to another as magnesium nitrate. aspect, the metal oxide is Selected from the group consisting 0.062 According to another aspect, the precursor Solution of Al-O, MgO, SiO2 and TiO2. According to another aspect, further comprises a precursor to alumina, Such as particulate the particulate absorbent material is in the form of Substan alumina. tially Spherical particles. 0.063. According to another aspect, the precursor Solution 0073. According to another aspect, the surface area is at further comprises a precursor to a metal Selected from the least about 10 m/g, Such as at least about 15 m/g or at least group consisting of Mg, Ni, Zn and Cu. about 30 m/g. 0064. According to another aspect, the heating step com 0074 According to another aspect, the particulate absor prises heating the precursor droplets to a temperature of at bent material has a pore volume of at least about 0.01 cm/g, least about 300° C. According to another aspect, the atom such as at least about 0.04 cm/g or at least about 0.15 cm/g. izing Step comprises atomizing the precursor Solution using 0075 According to another aspect, the metal oxide com a spray nozzle., According to another aspect, the atomizing prises from about 1 wt.% to 50 wt.% of the particulate Step comprises atomizing the precursor using ultrasonic absorbent material. transducers. According to another aspect, the particulate 0076 According to another aspect, where the metal oxide absorbent material has an average size of from about 1 um comprises from about 5 wt.% to about 25 wt.% of the to about 50 lum. particulate absorbent material. 0065 According to one aspect, the particulate absorbent material is pelletized. According to another aspect, the 0077 According to another aspect, the particulate absor particulate absorbent material is coated on a Support Struc bent compound has an absorption capacity of at least about 50 mol. 76 for at least one Selected chemical Species. ture. According to another aspect, the particulate absorbent com 0.066 According to another aspect, the particulate absor pound has an absorption capacity of at least about 70 mol. bent material has a Substantially Spherical morphology. % for at least one Selected chemical Species. According to US 2005/0230659 A1 Oct. 20, 2005 another aspect, the particulate absorbent compound has an 0086 According to another aspect, the precursor Solution absorption capacity of at least about 90 mol. 9% for at least further comprises a Second precursor, the Second precursor one Selected chemical Species. being Selected to form a metal Selected from the group consisting of Mg, Ni, Zn and Cu. 0078. According to another aspect, the absorbent com pound has an absorption capacity of at least about 50 mol. 0087. According to another aspect, the heating step com % for at least one Selected chemical-species after at least prises heating the precursor droplets to a temperature of at 100. cycles. According to another aspect, the absorbent least about 300° C. According to another aspect, the con compound has an absorption capacity of at least about 70 Verting Step comprised heating the intermediate compound. mol. 76 for at least one Selected chemical Species after at 0088 According to another aspect, the atomizing step least 100 cycles. According to another aspect, the absorbent comprises atomizing the precursor Solution using a Spray compound has an absorption capacity of at least about 90 nozzle. According to another aspect, the atomizing Step mol. 76 for at least one Selected chemical Species after at comprises atomizing the precursor Solution using ultrasonic least 100 cycles. transducers. 0079 According to another embodiment of the present 0089. According to another aspect, the particles have an invention, a method for the fabrication of a particulate average size of from about 1 um to about 50 lum. According absorbent material is provided. The method can include the to another aspect, the particulates have Substantially Spheri Steps of atomizing a liquid-containing precursor Solution to cal morphology. form precursor droplets, the precursor Solution comprising at least a first precursor to an absorbent compound, heating 0090 According to one aspect, the absorbent material the precursor droplets to form dried precursor droplets, and comprises CaO. According to another aspect, the absorbent converting the dried precursor droplets to an absorbent material comprises ZnO. According to another aspect, the material comprising an absorbent compound. absorbent material comprises LiO. 0080 According to one aspect, the heating step and the 0091. According to another embodiment of the present converting Step occur Sequentially in a spray pyrolysis invention, a method for the fabrication of a particulate NO operation. According to another aspect, the heating Step absorbent material is provided. The method includes the forms an intermediate compound capable of being post Steps of providing a precursor Solution comprising at least a processed to form a particulate absorbent material, and the first precursor to a NO absorbent compound, atomizing the converting Step comprises heating the intermediate com precursor Solution to form precursor droplets, heating the precursor droplets to form dried precursor droplets, and pound to form the particulate absorbent material. converting the dried precursor droplets to an absorbent 0081. According to another aspect, the first precursor is at material comprising an absorbent compound for NO. least partially Soluble in the precursor Solution. According to 0092 According to one aspect, the heating step and the another aspect, the first precursor is Selected from the group converting Step occur Sequentially in a Spray pyrolysis consisting of metal oxalates and metal hydroxides. Accord process. According to another aspect, the heating Step forms ing to another aspect, the first precursor is Selected from the an intermediate compound capable of being post-processed group consisting of calcium nitrate, calcium acetate, calcium to form a particulate absorbent material, and the converting oxalate and calcium hydroxide. According to another aspect, Step comprises heating the intermediate compound to form the first precursor comprises calcium oxalate. the particulate absorbent material. 0082) According to another aspect, the heating step com 0093. According to one aspect, the NO absorbent com prises heating the droplets in the presence of an oxygen pound comprises a compound Selected from the group containing gas. consisting of the oxides, hydroxides or carbonates of the 0.083. According to another aspect, the precursor Solution alkali metals, alkaline earth metals and lanthanide metals. further comprises a morphology-enhancing agent, Such as a 0094. According to one aspect, the NO absorbent com morphology-enhancing agent Selected from the group con pound comprises an oxide, hydroxide or carbonate of a Sisting of lactic acid, glycine, alcohols, ammonium nitrate, metal Selected from Na, K, Ca or Ba. According to another polymers and carbohydrazide. aspect, the NO absorbent compound comprises MnO:ZrO. 0084. According to another aspect, the precursor Solution According to another aspect, the NO absorbent compound further comprises a Second precursor, the Second precursor comprises CeO2. According to one aspect, the NO absor being Selected to form a compound Selected from the group bent compound comprises a Y-Ba-Cu-O compound. consisting of aluminum oxides, magnesium oxides, Silicon 0095 According to another embodiment, a method for oxides and titanium oxides. According to another aspect, the the fabrication of a particulate HS absorbent material is precursor Solution further comprises a Second precursor, the provided. The method includes the Steps of providing a Second precursor being Selected to form magnesium oxide. precursor Solution comprising at least a first precursor to a HS absorbent compound, atomizing the precursor Solution 0085. According to another aspect, the precursor Solution to form precursor droplets, heating the precursor droplets to further comprises a Second precursor comprising magne form a particulate NO absorbent compound and converting sium nitrate. According to another aspect, the precursor the dried precursor droplets to an absorbent material com Solution further comprises a Second precursor, the Second prising an absorbent compound. precursor being Selected to form alumina. According to another aspect, the precursor Solution further comprises a 0096. According to one aspect, the heating step and the Second precursor comprising particulate alumina. converting Step occur Sequentially in a Spray pyrolysis US 2005/0230659 A1 Oct. 20, 2005 process. According to another aspect, the heating Step forms 0109 FIG. 9 illustrates the aggregate particle morphol an intermediate compound capable of being post-processed ogy of a Supported absorbent material according to an to form a particulate absorbent material, and the converting embodiment of the present invention. Step comprises heating the intermediate compound to form the particulate absorbent material. 0110 FIG. 10 illustrates the aggregate particle morphol ogy of an absorbent material according to an embodiment of 0097 According to one aspect, the HS absorbent com the present invention. pound comprises CaO. According to another aspect, the HS absorbent compound comprises ZnO. 0111 FIG. 11 illustrates the particle size distribution of absorbent powders according to the present invention com 0098. According to another embodiment of the present pared to the prior art. invention, a method for the fabrication of a reversible hydrogen Storage material is provided. The method includes 0112 FIG. 12 illustrates the BET surface area of absor the Steps of providing a precursor Solution comprising at bent powders according to the present invention compared least a first precursor to a hydrogen Storage compound, to the prior art. atomizing the precursor Solution to form precursor droplets, heating the precursor droplets to form dried precursor drop 0113 FIG. 13 illustrates the pore volume of absorbent lets, and converting the dried precursor droplets to an powders according to the present invention compared to the absorbent material comprising an absorbent compound. prior art. 0099. According to one aspect, the heating step and the 0114 FIG. 14 illustrates the particle size distribution of converting Step occur Sequentially in a spray pyrolysis Zn-based absorbent powders according to the present inven process. According to another aspect, the heating Step forms tion. an intermediate compound capable of being post-processed 0115 FIG. 15 illustrates the pore volume, BET surface to form a particulate absorbent material, and the converting area and pore diameter of Zn-based absorbent powders Step comprises heating the intermediate compound to form according to the present invention. the particulate absorbent material. 0100 According to another aspect, the hydrogen Storage 0116 FIGS. 16(a) and 16(b) illustrate SEM photomicro compound comprises a misch metal, Such as one Selected graphs for a Zn-oxide absorbent powder according to the from the group consisting of LaNis, Mg-Ni, Mg2Fe, TFe, present invention. and ZrMn. According to another aspect, the hydrogen 0117 FIGS. 17(a) and 17(b) illustrate SEM photomicro Storage compound comprises a metal hydride, Such as one graphs for a Zn-oxide absorbent powder according to the Selected from the group consisting of NaBH, AlH, LiAlH present invention. and Mg(AlH). According to another embodiment, the hydrogen Storage compound comprises an alkali metal 0118 FIGS. 18(a) and 18(b) illustrate SEM photomicro nitride. graphs of a Zn-based powder according to the present invention. DESCRIPTION OF THE DRAWINGS 0119 FIG. 19 illustrates the particle size distribution of 0101 FIG. 1 schematically illustrates a spray pyrolysis Zn-based absorbent powders according to the present inven method for the fabrication of Ca-based particles according to tion. an embodiment of the present invention. 0120 FIG. 20 illustrates the pore volume and BET 0102 FIG. 2 schematically illustrates a spray conversion Surface area of Zn-based absorbent powders according to the method for the fabrication of Ca-based particles according to present invention. an embodiment of the present invention. 0121 FIG. 21 illustrates the average pore diameter for 0103 FIG. 3 schematically illustrates a post-processing Zn-based absorbent powders according to the present inven method for the fabrication of Ca-based particles according to tion. an embodiment of the present invention. 0.122 FIG. 22 illustrates the particle size distribution for 0104 FIG. 4 schematically illustrates a spray conversion Zn-based composite absorbent powders according to the method for the fabrication of Zn-based particles according to present invention. an embodiment of the present invention. 0105 FIG. 5 schematically illustrates a post-processing 0123 FIG. 23 illustrates the pore volume, average pore method for the fabrication of Zn-based particles according to diameter and BET surface area of Zn-based composite an embodiment of the present invention. absorbent powders according to the present invention. 0106 FIG. 6 illustrates a process of the absorption of a 0.124 FIG. 24 illustrates the carbonation and decarbon contaminant from a gas Stream with a regenerating Step. ation kinetics of a commercial CaO powder according to the prior art. 0107 FIG. 7 illustrates the aggregate particle morphol ogy of a particulate absorbent material according to an 0125 FIG. 25 CO illustrates the absorption capacity of embodiment of the present invention. a commercial CaO absorbent powder over 26 cycles. 0108 FIG. 8 illustrates the aggregate particle morphol 0.126 FIG. 26 illustrates the particle size distribution of ogy of a particulate absorbent material according to an a commercial CaO absorbent powder before and after 27 embodiment of the present invention. cycles. US 2005/0230659 A1 Oct. 20, 2005 0127 FIG. 27 illustrates the pore volume, BET surface 014.5 FIG. 45 illustrates the absorption capacity of pel area and average pore Size of a commercial CaO absorbent letized absorbent powders according to the present inven powder before and after 27 cycles. tion. 0128 FIG. 28 illustrates the absorption capacity in terms 0146 FIG. 46 illustrates the carbonation and decarbon of CaO reaction fraction of CaO-based absorbents over 8 ation kinetics of pelletized absorbent powders according to cycles according to the present invention compared to the the present invention. prior art. 0147 FIG. 47 illustrates the absorption capacity in terms 0129 FIG. 29 illustrates the carbonation and decarbon of CaO reaction fraction of pelletized absorbent powders ation kinetics of CaO-based absorbents according to the according to the present invention over 116 cycles. present invention compared to the prior art. 0.148 FIG. 48 illustrates the absorption capacity of pel 0130 FIG. 30 illustrates the particle size distribution of letized absorbent powders according to the present invention absorbent powders according to the present invention. over 116 cycles. 0131 FIG. 31 illustrates the pore volume, BET surface 014.9 FIG. 49 illustrates the absorption capacity in terms area and average pore diameter for absorbent powders of CaO reaction fraction of pelletized absorbent powders according to the present invention. according to the present invention over multiple cycles. 0132 FIG. 32 illustrates the absorption capacity in terms 0150 FIG. 50 illustrates the absorption capacity of pel of CaO reaction fraction of absorbent powders according to letized absorbent powders according to the present invention the present invention over 12 cycles. over multiple cycles. 0133 FIGS. 33(a) and 33(b) illustrate SEM photomicro 0151 FIG. 51 illustrates the absorption capacity in terms graphs of a commercial CaO powder before and after 27 of CaO reaction fraction of pelletized absorbent powders cycles. according to the present invention over multiple cycles. 0134 FIGS. 34(a) and 34(b) illustrate SEM photomicro 0152 FIG. 52 illustrates the absorption capacity of pel graphs of an absorbent powder according to the present letized absorbent powders according to the present invention invention before and after 12 cycles. over multiple cycles. 0135 FIGS. 35(a) and 35(b) illustrate SEM photomicro 0153 FIG. 53 illustrates the absorption capacity in terms graphs of an absorbent powder according to the present of CaO reaction fraction of pelletized absorbent powders invention before and after 12 cycles. according to the present invention over multiple cycles. 0136 FIG. 36 illustrates the particle size distribution of 0154 FIG. 54 illustrates the absorption capacity over 66 absorbent powders according to the present invention before cycles of pelletized absorbent powders according to the and after 12 cycles. present invention. 0.137 FIG. 37 illustrates the absorption capacity in terms 0155 FIG.55 illustrates the absorption capacity over 66 of CaO reaction fraction of absorbent powders according to cycles in terms of CaO reaction fraction of pelletized the present invention over 12 cycles. absorbent powders according to the present invention. 0138 FIG. 38 illustrates the carbonation and decarbon 0156 FIG. 56 illustrates the absorption capacity over 66 ation kinetics of Several absorbent powders according to the cycles of pelletized absorbent powders according to the present invention. present invention. 0157 FIG. 57 illustrates the absorption capacity over 66 0139 FIG. 39 illustrates the carbonation and decarbon cycles in terms of CaO reaction fraction of pelletized ation kinetics of a composite absorbent powder according to absorbent powders according to the present invention over the present invention. multiple cycles. 0140 FIG. 40 illustrates the adsorption capacity over 12 0158 FIG. 58 illustrates the absorption capacity over 66 cycles for 2 absorbent materials according to the present cycles of pelletized absorbent powders according to the invention. present invention. 0141 FIG. 41 illustrates the carbonation and decarbon 0159 FIG. 59 illustrates the absorption capacity over 64 ation kinetics of absorbent powders according to the present cycles in terms of CaO reaction fraction of pelletized invention. absorbent powders according to the present invention. 0142 FIG. 42 illustrates the particle size distribution of 0160 FIG. 60 illustrates the absorption capacity over 64 absorbent powders according to the present invention before cycles in terms of CaO reaction fraction of pelletized and after 12 cycles. absorbent powders according to the present invention. 0143 FIG. 43 illustrates the pore volume, BET surface 0.161 FIG. 61 illustrates the absorption capacity over 64 area and average pore diameter of absorbent powders cycles in terms of CaO reaction fraction of pelletized according to the present invention before and after 12 absorbent powders according to the present invention. regeneration cycles. 014.4 FIG. 44 illustrates the absorption capacity in terms DESCRIPTION OF THE INVENTION of CaO reaction fraction of pelletized absorbent powders 0162 The present invention is directed to improved according to the present invention. materials and methods for making the materials that are US 2005/0230659 A1 Oct. 20, 2005 particularly useful for the absorption of a chemical Species nent of the liquid precursor is chemically converted into a such as HS, CO., NO, H and others from a fluid stream desired component of the powder. In spray pyrolysis, the Such as a liquid or gaseous Stream. The materials can chemical conversion occurs within the reactor into which the include, but are not limited to, metal oxides Such as Group Solution is sprayed. In spray conversion, the precursor is 1 and Group 2 metal oxides, metals, metal mixtures, metal partially converted to form an intermediate compound, and alloys, metal hydrides, molecular compounds, carbon mate the intermediate compound is converted to the final material rials, lithium Silicates, lithium Zirconates and others. in a post-processing Step. 0163 The “absorption” of one species by an absorbent 0168 According to one embodiment of the present inven material can occur by a variety of different mechanisms and tion, the absorbent compound can be selected from metal is often described using a number of different terms which oxides, and in particular can be Selected from Group 1 and can often lead to confusion. In the present application, the Group 2 metal oxides. Examples of Group I metal oxides word absorption and the process of absorption is used in the include lithium oxide, Sodium oxide and potassium oxide. broadest Sense to include at least physisorption, chemical Examples of Group 2 metal oxides include magnesium absorption and absorption with chemical reaction. oxide, calcium oxide, Strontium oxide and barium oxide. 0164 Physisorption of a molecular species on the surface Particularly preferred among these for CO2 absorption are of a Solid includes an interaction that is primarily a physical the Group 2 metal oxides, particularly calcium oxide. interaction and is largely a result of Van der Waals interac Lithium oxide is also preferred for Some applications. It will tions. An example of this type of interaction is the phySorp be appreciated that other metal oxide compounds may be tion of H molecules on a carbon Surface or the intercalation useful for the absorption of a particular chemical Species of a molecular species in a porous Solid Such as a molecular (e.g., silver oxide), and Such metal oxide compounds are Sieve. Chemical adsorption of a molecular Species on a also within the Scope of the present invention. The preferred Surface, typically includes dissociative adsorption where the absorbent compound will depend upon a number of factors, adsorbed Species is chemically bonded to the Surface of the particularly the absorption temperature that is utilized for a adsorbent. An example of this type of chemical adsorption given absorption process. Accordingly, CaO is a preferred is the dissociation of a molecular species on the Surface of absorbent compound for CO absorption at temperatures in a metal, or water on the Surface of Silica to form Surface the range of 500° C. to about 900° C. Lithium oxide and hydroxyl groups. Absorption and chemical reaction of a magnesium oxide can be preferred for use at lower tem molecular species can occur with the bulk of the absorbent peratures. These temperature ranges can change if the absor to form a new, typically Stoichiometric compound. An bent compound is mixed with an inert material. For example of this kind of process is the reaction of ZnO with example, CaO can be mixed with TiO, to increase the useful HS to form ZnS and H2O. This kind of bulk absorption absorption temperature to about 1100 C. typically occurs via the first two processes described above, 0169. Another factor governing the selection of an absor physiorption on the Surface followed by chemical reaction bent compound is the theoretical absorption capacity of the with the Surface and/or diffusion into the bulk of the material absorbent compound. It is preferred to use an absorbent until the reaction is complete. AS used herein, the term compound having the highest absorption capacity whenever absorption, absorbent or Similar terms refer generally to all possible. of the foregoing mechanisms. 0170 It will also be appreciated that a physical mixture 0165. Overview of Spray Processing of two or more absorbent compounds can be utilized provide 0166 The absorbent materials of the present invention an absorbent mixture that has desirable absorption properties are preferably fabricated by Spray drying, Spray conversion over a wide range of absorption conditions, Such as tem or spray pyrolysis methods, which are collectively referred perature, or to absorb more than one chemical Species in a to herein as spray processing methods. The Spray processing Single reactor Space. methods of the present invention are capable of producing a 0171 Spray processing precursors for such metal oxide wide variety of absorbent materials and desired microstruc compounds can include metal Salts, Such as metal nitrates, tures. The major attribute of this approach is the ability to oxalates, acetates and hydroxides. Thus, particularly pre fabricate compositions and microstructures that cannot be ferred precursors include Group 2 metal nitrates, Group 2 fabricated by other powder manufacturing methods, com metal oxalates, Group 2 metal acetates and Group 2 metal bined with the ability to economically produce high volumes hydroxides. For Some applications, Group 2 metal oxalates of absorbent material. The flexibility to fabricate unique are particularly preferred. combinations of compositions and microStructures comes from the fact that Spray processing combines aspects of both 0172 CaO is one preferred absorbent compound accord liquid phase and Solid State processing. ing to the present invention. Preferred spray processing 0167 Spray processing generally includes the steps of precursors for CaO can be selected from calcium metal Salts providing a precursor composition, typically in a flowable Such as calcium nitrate Ca(NO), calcium oxalate CaCO, liquid form. The precursor composition typically includes at calcium acetate Ca(CHO) and calcium hydroxide least a precursor to the absorbent material. In the case of Ca(OH). Supported absorbent materials, the precursor composition 0173 Another preferred absorbent compound according can also include a precursor to or a Suspension of the Support to one embodiment of the present invention is Zinc oxide phase. The precursor composition is atomized to form a (ZnO), which is particularly useful for the absorption of Suspension of liquid precursor droplets and the liquid is H.S. Preferred spray processing precursors for ZnO can be removed from the liquid precursor droplets, Such as by Selected from Zinc metal Salts Such as Zinc nitrate, Zinc heating, to form the powder. Typically, at least one compo oxalate, Zinc acetate and Zinc hydroxide. US 2005/0230659 A1 Oct. 20, 2005 0.174. Other preferred absorbent compounds include, for method illustrated in FIGS. 2 and 4 followed by a method example, copper oxide, Silver oxide, barium oxide, barium such as that illustrated in FIGS. 3 and 5. By varying carbonate, nickel oxide, iron oxide and lithium oxide. Pre reaction time, temperature and type of precursors, the Spray ferred Spray processing precursors for these materials can processing methods can produce powder morphologies and include metal organic compounds (e.g., metal carboxylates), absorbent material Structures that yield improved perfor inorganic compounds (e.g., metal nitrates) and organome CC. tallic compounds (e.g., olefin complexes and metal acetates). 0181. When the absorbent compound is dispersed on an 0.175. It is often desirable to form the absorbent material inert Support in the form of absorbent material clusters, the with a high level of porosity or crystallinity, and, therefore, precursor composition can include particulates that form the it may be advantageous to include a morphology enhancing inert Support phase. According to the present invention, Such agent in the precursor composition to enhance the porosity particulates can include particulate carbon or particulate or crystallinity of the powder. Preferred morphology metal oxides, Such as aluminum oxide (e.g., boehmite) enhancing agents can be Selected from lactic acid, glycine, fumed metal oxides and aerogels. Preferably, Such particu alcohols, ammonium nitrate, polymers and carbohydrazide. lates have an average size of at least about 50 nm and not The amount of morphology enhancing agent in the precursor greater than about 200 nm. solution, if used, can preferably be varied from about 0.05 0182 Preferably, the supported absorbent material phase Vol.% to about 20 Vol.%, expressed as a percentage of the is formed while the precursor to the absorbent material total Volume of the precursor Solution. phase is in intimate contact with the Surface of the Support 0176) Other compounds can be included in the absorbent phase particles and the absorbent material precursor is materials according to the present invention, as is discussed rapidly reacted on the Surface of the Support phase particles. in more detail below. Included among these are aluminum The reaction and formation of the Supported absorbent oxides, magnesium oxides, Silicon oxides or titanium material preferably occurs over a very short period of time oxides. Precursors for Such materials can include nitrate Such that the growth of large active material clusters is Salts, Such as aluminum, nitrate Al(NO-) or magnesium limited. Preferably, the absorbent material precursor is nitrate Mg(NO), as well as particulate dispersions of the exposed to the elevated reaction temperature to form the metal oxides (e.g., fumed metal oxides) or precursors to the absorbent material for not more than about 600 seconds, metal oxides (e.g., boehmite). In addition, the absorbent more preferably not more than about 100 seconds and even material can include other metals Such as iron, magnesium, more preferably not more than about 10 seconds. The means Zinc, manganese, cobalt and copper. Precursors for these by which the absorbent material precursor is reacted is metals can be Selected from the metal nitrates, Sulfates, discussed in detail below. carbonates, acetates, oxalates, hydroxides and metal oxide 0183 Preferably, the spray processing methods are nanoparticles, including fumed metal oxides. capable of forming a spherical particle Structure. The Spheri 0177 Although the following description refers primarily cal particles form as a result of the formation and drying of to the production of CaO by Spray processing, it will be the precursor droplets during spray processing. Spherical appreciated that the proceSS is generally applicable to other particles can advantageously enhance the particle packing absorbent materials. characteristics in a packed powder bed, and can be advan tageous in the formation of extrudates, pellets or monoliths. 0.178 The spray processing methods can combine the drying of the precursors and the conversion to the absorbent 0.184 Spray processing methods for the production of the material in one step, where both the removal of the solvent absorbent compounds and other components of the absor and the conversion of a precursor occur essentially simul bent material can be grouped by reference to Several differ taneously. This method is referred to as Spray pyrolysis, and ent attributes of the apparatus used to carry out the method. is schematically illustrated in FIG. 1 for the fabrication of These attributes include: the main gas flow direction (ver CaO. In another embodiment, the Spray processing method tical or horizontal); the type of atomizer (Submerged ultra achieves the drying of the precursors and a partial conver Sonic, ultraSonic nozzle, two-fluid nozzle, Single nozzle Sion of the precursors to an intermediate compound. This pressurized fluid); the type of gas flow (e.g., laminar with no method is schematically illustrated in FIG. 2 for the fabri mixing, turbulent with no mixing, co-current of droplets and cation of an intermediate compound to CaO. The complete hot gas, countercurrent of droplets and gas or mixed flow); conversion to the absorbent compound and/or the crystalli the type of heating (e.g., hot wall System, hot gas introduc Zation of the material can occur in a Second Step, Such as the tion, combined hot gas and hot wall, plasma or flame); and step that is schematically illustrated in FIG. 3 for CaO. This the type of powder collection System (e.g., cyclone, bag Second step is referred to herein as post-processing, and house, electrostatic or settling). typically includes heating the particles that include the 0185. For example, the absorbent material powders of the intermediate compound. present invention can be prepared by Starting with a precur 0179 A spray processing method to achieve drying of the Sor liquid, Such as an aqueous-based liquid, including a precursors and a partial conversion of the precursors to an dissolved, metal Salt and/or a dispersion of particulates that intermediate compound for the fabrication of ZnO from are either inert materials or intermediate compounds to the Zn-nitrate is schematically illustrated in FIG. 4. The post absorbent compounds. The processing temperature of the processing of the intermediate compound to form ZnO is precursor droplets can be controlled So the metal Salt pre cursor decomposes to form the absorbent material, a Solid illustrated in FIG. 5. precursor (intermediate compound) to the absorbent mate 0180 Thus, spray drying or spray conversion can be rial, or a combination of the intermediate compound and the followed by conventional heating or calcination, e.g., a absorbent material. US 2005/0230659 A1 Oct. 20, 2005 0186 The first step in the process is the evaporation of Some advantages over Single or two-fluid nozzles Such as the the Solvent as the droplet is heated resulting in a particle of low velocity of the Spray leaving the nozzle and lack of dried Solids and/or metal salts. A number of methods to asSociated gas flow. The nozzles are available with various deliver heat to the particle are possible: horizontal hot-wall orifice sizes and orifice diameters that allow the System to be tubular reactors, Spray dryer and Vertical tubular reactors can Scaled for the desired production capacity. In general, higher be used, as well as plasma, flame and laser reactors. Hori frequency nozzles are physically Smaller, produce Smaller Zontal hot-wall tubular reactors are disclosed in U.S. Pat. droplets, and have a lower flow capacity than nozzles that No. 6,103,393 by Kodas et al. and are referred to herein as operate at lower frequencies. A drawback of ultrasonic Spray pyrolysis reactors. Spray dryers are disclosed, for nozzle Systems is that Scaling up the proceSS by increasing example, in U.S. Pat. No. 5,615,493 by Funder and U.S. Pat. the nozzle Size increases the average particle size. If a No. 5,100,509 by Pisecky et al. A plasma reactor is disclosed particular particle size is required, then the maximum pro in U.S. Pat. No. 6,689,192 by Phillips et al. and a flame duction rate per nozzle is Set. If the desired production rate reactor is disclosed in U.S. Pat. No. 5,958,361 by Laine et exceeds the maximum production rate of the nozzle, addi al. Laser reactors are disclosed in U.S. Pat. No. 6,248,216 by tional nozzles or additional production units are required to Bi et al. Each of the foregoing U.S. Patents is incorporated achieve the desired production rate. herein by reference in its entirety. 0.192 The shape of the atomizing surface determines the 0187. As the particles experience either higher tempera shape and spread of the Spray pattern. Conical, microSpray ture or longer time at a specific temperature, the precursors and flat atomizing Surface shapes are available. The conical decompose. Preferably, the time that the droplets/particles atomizing Surface provides the greatest atomizing capability experience a given temperature can be controlled and there and has a large spray envelope. The flat atomizing Surface fore the degree of porosity, crystallinity, the microStructure provides almost as much flow as the conical Surface but and other properties can also be controlled. limits the overall diameter of the Spray. The microSpray 0188 The atomization technique for generating the pre atomizing Surface is for very low flow rates where narrow cursor droplets has a Significant influence over the charac Spray patterns are needed. These nozzles are preferred for teristics of the final absorbent material powder, Such as the configurations where minimal gas flow is required in asso particle Surface area, porosity, size, the Spread of the particle ciation with the droplets. size distribution (PSD), as well as the production rate of the 0193 Particulate suspensions in the precursor Solution powder. In extreme cases, Some techniques cannot atomize (e.g., for the production of a Supported active material) may fluids with even moderate particle loadings or high Viscosi present Several problems with respect to atomization. For ties. Several methods exist for the atomization of precursor example, Submerged ultraSonic atomizers re-circulate the compositions, including those that contain Suspended par Suspension through the generation chamber and the Suspen ticulates. These methods include but are not limited to: Sion concentrates over time. Further, Some fraction of the ultraSonic transducers (usually at a frequency of 1-3 MHz); liquid atomizes without carrying the Suspended particulates. ultrasonic nozzles (usually at a frequency of 10-150 KHz); Other problems encountered when using Submerged ultra rotary atomizers, two-fluid nozzles, and pressure atomizers. Sonic transducers is that the transducer discS can become 0189 Ultrasonic transducers are generally submerged in coated with the particles and or precursor over time. Further, a liquid and the ultraSonic energy produces atomized drop the generation rate of particulate Suspensions can be very lets on the surface of the liquid. Two basic ultrasonic low using Submerged ultraSonic transducer discs. This is due transducer disc configurations, planar and point Source can in part to energy being absorbed or reflected by the Sus be used. Deeper fluid levels can be atomized using a point pended particles. Source configuration Since the energy is focused at a point 0194 For spray drying, the aerosol can be generated that is Some distance above the Surface of the transducer. The using three basic methods. These methods differ in the type Scale-up of Submerged ultrasonic transducers can be accom of energy used to break the liquid masses into Small droplets. plished by placing a large number of ultraSonic transducers Rotary atomizers (utilization of centrifugal energy) make in an array. Such a system is illustrated in U.S. Pat. No. use of Spinning liquid droplets off of a rotating wheel or disc. 6,103,393 by Kodas et al. and U.S. Pat. No. 6,338,809 by Rotary atomizers are useful for co-current production of Hampden-Smith et al., and the disclosure of each of these droplets in the range of 20 um to 150 um in diameter. U.S. Patents is incorporated herein by reference in its Pressure nozzles (utilization of pressure energy) generate entirety. droplets by passing a fluid under high pressure through an 0.190 Scale-up of nozzle systems can be accomplished by orifice. These can be used for both co-current and -mixed either Selecting a nozzle with a larger capacity or by increas flow reactor configurations and typically produce droplets in ing the number of nozzles used in parallel. Typically, the the size range of 50 um to 300 lum. Multiple fluid nozzles droplets produced by nozzles are larger than those produced Such as a two-fluid nozzle produce droplets by passing a by ultraSonic transducers. Particle size is also dependent on relatively slow moving fluid through an orifice while shear the gas flow rate. For a fixed liquid flow rate, an increased ing the fluid Stream with a relatively fast moving gas Stream. airflow decreases the average droplet Size and a decreased AS with pressure nozzles, multiple fluid nozzles can be used airflow increases the average droplet size. It is difficult to with both co-current and mixed-flow Spray dryer configu change droplet size without varying the liquid or airflow rations. This type of nozzle can typically produce droplets in rates. However, two-fluid nozzles have the ability to process the size range of 5 um to 200 um. larger Volumes of liquid per time than ultraSonic transducers. 0.195 For example, two-fluid nozzles are used to produce 0191 Ultrasonic spray nozzles also use high frequency aeroSol Sprays in many commercial applications, typically in energy to atomize a fluid. UltraSonic Spray nozzles have conjunction with Spray drying processes. In a two-fluid US 2005/0230659 A1 Oct. 20, 2005 nozzle, a low-velocity liquid Stream encounters a high evaporating the liquid to produce a dry aeroSol, wherein Velocity gas Stream that generates high shear forces to thermal decomposition of one or more precursors may take accomplish atomization of the liquid. A direct result of this place to produce the powder. The residence time in the Spray interaction is that the droplet Size characteristics of the dryer is the average time the process gas Spends in the drying aeroSol are dependent on the relative mass flow rates of the vessel as calculated by the vessel volume divided by the liquid precursor and nozzle gas Stream. The Velocity of the process gas flow using the outlet gas conditions. The peak droplets as they leave the generation Zone can be quite large excursion temperature (i.e., the reaction temperature) in the which may lead to unacceptable losses due to impaction. Spray dryer is the maximum temperature of a particle, The aerosol also leaves the nozzle in a characteristic pattern, averaged throughout its diameter, while the particle is being typically a flat fan, and this may require that the dimensions processed and/or dried. The droplets are heated by Supplying of the reactor be Sufficiently large to prevent unwanted a pre-heated carrier gas. losses on the walls of the System. 0202 Three types of spray dryer systems are useful for 0196. Thus, numerous atomization techniques for spray the Spray drying of the absorbent material powders accord processing are possible for the production of absorbent ing to the present invention. An open System is useful for material powders and different versions are preferred for Spray drying of powders using air as an aeroSol carrier gas different feed Streams and products. and an aqueous feed Solution as a precursor. A closed System is useful for Spray drying of powders using an aerosol carrier 0197) The atomized precursor composition must be gas other than air. A closed System is also useful when using heated to remove Solvents and react precursor components. a non-aqueous or a Semi-non-aqueous Solution as a precur For example, a horizontal, tubular hot-wall reactor can be Sor. A Semi-closed System, including a Self-inertizing Sys used to heat a gas Stream to a desired temperature. Energy tem, is useful for Spray drying of powders that require an is delivered to the System by maintaining a fixed boundary inert atmosphere and/or precursors that are potentially flam temperature at the wall of the reactor and the maximum mable. temperature of the gas is the wall temperature. Heat transfer within a hot wall reactor occurs through the bulk of the gas. 0203 Two spray dryer designs are, particularly useful for Buoyant forces that occur naturally in horizontal hot wall the production of the absorbent material powders of the reactorS aid this transfer. The mixing also helps to improve present invention. A co-current Spray dryer is useful for the the radial homogeneity of the gas Stream. Passive or active production of materials that are Sensitive to high temperature mixing of the gas can also increase the heat transfer rate. The excursions (e.g., greater-than about 350° C.) or that require maximum temperature and the heating rate can be controlled a rotary atomizer to generate the aeroSol. Mixed-flow Spray independent of the inlet Stream with Small changes in dryers are useful for producing materials that require rela residence time. The heating rate of the inlet Stream can also tively high temperature excursions (e.g., greater than about be controlled using a multi-Zone furnace. 350° C.) or require turbulent mixing forces. 0198 The use of a horizontal hot-wall reactor according 0204. In a co-current spray dryer, the hot gas is intro to the present invention is generally preferred to produce duced at the top of the unit where the droplets are generated particles with a size of not greater than about 5 um. Above with any of the atomization techniques mentioned above. about 5 um, Settling of particles can cause significant mate The maximum temperature that a droplet/particle is exposed rial losses. One disadvantage of Such reactors is the poor to in a co-current spray dryer is the temperature of the outlet. ability to atomize particulates when using Submerged ultra Typically, the outlet temperature is limited to about 200 C., Sonics for atomization. although Some designs allow for higher temperatures. In addition, Since the particles experience the lowest tempera 0199 Alternatively, the horizontal hot-wall reactor can ture in the beginning of the time-temperature curve and the be used with a two-fluid nozzle to atomize the droplets. This highest temperature at the end, the possibility of precursor approach is preferred for precursor feed Streams containing Surface diffusion and agglomeration is high. higher levels of particulate materials, Such as a particulate Support precursor. A horizontal hot-wall reactor can also be 0205. A preferred spray processing System according to used with ultraSonic nozzle atomization techniques. This the present invention is based on a mixed-flow Spray dryer. allows atomization of a precursor containing particulates, A mixed-flow Spray dryer introduces the hot gas at the top however the large droplet size leads to losses of materials on of the unit and the precursor droplets are generated near the reactor walls and other Surfaces making this an expensive bottom and are directed upwardly. The droplets/particles are method for powder production. forced towards the top of the unit then fall and flow back down with the gas, increasing the residence time in the Spray 0200 While horizontal hot-wall reactors are specifically dryer. The temperature the particles experience is also higher useful for Some particle morphologies and compositions as compared to a co-current spray dryer. This is important, according to the present invention, particularly for the Spray as most Spray dryers are not capable of reaching the higher pyrolysis method illustrated in FIG. 1, Spray processing temperatures that are required for the conversion of Some Systems in the configuration of a spray dryer are the pre precursor Salts. ferred production method for large quantities of absorbent powders in accordance with Some applications of the present 0206 For mixed flow spray dryers the reaction tempera invention. Such spray processing Systems are particularly tures can be high enough for the decomposition of metal useful for the Spray conversion method Schematically illus precursors. The highest temperature in these spray dryerS is trated in FIGS. 2 and 4. the inlet-temperature (e.g., 600 C. and higher), and the outlet temperature can be as low as 90° C. Therefore, the 0201 Spray drying is a process wherein powders are particles: reach the highest temperature for a relatively short produced by atomizing a precursor to produce droplets and time, which advantageously reduces precursor migration or US 2005/0230659 A1 Oct. 20, 2005 Surface diffusion, Such as for Supported absorbent com of the material. A number of methods can be used to effect pounds. This Spike of high temperature quickly converts the this thermal transformation including heat treatment in a precursor and is followed by a mild quench Since the Spray Static bed or a moving bed. dryer temperature quickly decreases after the maximum temperature is achieved. The Spike-like temperature profile 0213. One preferred embodiment of the post-processing is advantageous for the generation of highly dispersed metal in a moving bed is the use of a rotary calciner in which the or metal oxide absorbent material clusters on the Surface of powder is delivered to a furnace which contains a rotating a Support phase. reactor tube Such that the bed of particles is constantly 0207. The range of useful residence times for producing moving to avoid particle to particle agglomeration and also the absorbent material powderS depends on the Spray dryer provide a fresh exposure of the Surface of the particle bed to design type, atmosphere used, nozzle configuration, feed allow outgassing of the material. This continual “agitation' liquid inlet temperature and the residual moisture content. In of the powder bed avoids depth-dependant variations in the general, residence times for the production of the absorbent Sample that can occur with a fixed bed reactor. material powders can range from 5 Seconds up to 5 minutes. 0214) A simple illustration of one cycle of the reaction According to one embodiment, the residence time is from and regeneration of an absorbent powder is illustrated in about 15 seconds to about 45 seconds. FIG. 6. Referring to FIG. 6, an activated absorbent bed 0208. The range of inlet temperatures for producing the comprising the absorbent powder is packed into a reactor. absorbent material powderS depends on the Spray dryer The absorbent bed can include loose absorbent powder, design type, atmosphere used, nozzle configuration, feed pelletized absorbent powder or a Surface coated with absor liquid, and energy required to perform drying and/or decom bent powder. A gas Stream is admitted to the reactor and the position functions. absorbent powder reacts Selectively with a component of the gas Stream, Such as H2S. Further reaction between the 0209. In general, the outlet temperature of the spray dryer absorbent powder and the gas Stream eventually consumes determines the residual moisture content of the powder. For substantially all of the available absorbent compound. Fur the production of the absorbent powders according to the ther use of this reactor under these conditions will not present invention, the range of useful outlet temperatures remove additional components from the gas Stream and the depends on the Spray dryer design type, atmosphere used, contaminated gas will pass through the reactor. The feed is nozzle configuration, feed liquid, inlet temperature, and then stopped and a regeneration gas, for example air and residual moisture content. For example, a useful outlet water, is passed through the reactor, which is heated to an temperature according to one embodiment of the present elevated temperature, to reverse the reaction, desorb the invention is at least about 200 C., such as at least about captured chemical Species and thereby regenerate the active 300° C., such as from about 200° C. to about 350° C. According to one embodiment, the temperature is at least absorbent bed. about 600 C. 0215. The primary issue affecting recyclability is that, generally, the reacted absorbent has a much lower density 0210. Other equipment that is desirable for producing the than the active absorbent. Therefore, for a fixed mass of absorbent material powders using a spray dryer includes a absorbent in a reactor bed, there is a large Volume increase heater for the gas and a collection System. Either direct as the absorbent is converted to the reacted absorbent. Due heating or indirect heating, including burning fuel, heating to the high temperature typically required for cycling the electrically, liquid-phase heating or Steam heating, can reacted absorbent back to the active absorbent, particle accomplish heating of the gas. The most useful type of Sintering and reduction of porosity occurs, leading to a heating for the production of powders processed with an reduced absorption capacity on Subsequent cycles. There inlet temperature greater than 350° C. is direct fuel burning. fore, a high initial absorption capacity through the produc 0211 Many collection methods are useful for collecting tion of a high Surface area absorbent powder will not, by powders produced on a Spray dryer. These methods include, itself, lead to retention of a high capacity during Subsequent but are not limited to those using cyclone, bag/cartridge cycles. Decrepitation is also common and leads to plugging filter, electroStatic precipitator, and various wet collection of the bed. techniques. 0216) In the context of the cyclic nature of the absorption/ 0212. The powders may also be post-processed by con desorption process, both the kinetics and the mechanism of ventional calcination methods to convert them into another the reactions are important. In order to achieve a high chemical composition and/or to crystallize the material. For absorption capacity, it is necessary to use a material having example, it may be advantageous to convert a metal oxalate a high content of active absorbent compound, Such as CaO. with a particular structure into a metal carbonate and/or However, a number of design criteria need to be taken into further to a metal oxide through a thermal post-processing account involving the chemical, physical and System aspects step (FIG. 3). Likewise, it may be advantageous to convert of the reversible reaction bed. These aspects include the a metal carbonate to a metal oxide while retaining the careful design of the microStructure of the material to beneficial attributes of the pore Structure. The post proceSS decrease diffusion-based limitations associated with gas ideally needs to be carried out under conditions that are not transport and Surface diffusion through the Substantially detrimental to the Structure and performance of the absor impervious Surface layer formed by reaction of the absor bent material. Where the post processing is a thermally bent, the chemical composition and microStructure to adjust induced transformation, the temperature needs to be care the rate constants of the reactions and the Strength of the fully chosen to effect the chemical change, without inducing material in pelletized and/or coated form. AS is discussed Significant Sintering or significantly altering the performance above, one of the critical issues to overcome is the change US 2005/0230659 A1 Oct. 20, 2005 in density and therefore microStructure and porosity on conversion methods (the intermediate compounds, or the cycling between the active absorbent and the reacted absor final absorbent material) is preferably not greater than about bent. 150 um, more preferably not greater than about 100 um, more preferably not greater than about 50 lum, not greater 0217 Current reactive absorbents suffer from a rapid loss than about 20 tim, more preferably not greater than about 10 of porosity from Sintering during multiple temperature tim and even more preferably not greater than about 5 um. Swing operations. The materials prepared by conventional Further, the average particle size is preferably at least about methods, Such as precipitation or Solid-State processing, 0.1 um and more preferably is at least about 0.3 um. either lack the desired porosity or the desired crystal size, which are two critical parameters to material performance. 0221) The surface area of the absorbent material powders An absorbent lacking adequate porosity will result in Slow will depend on the composition of the absorbent material. kinetics for both absorption and desorption of the target However, the Surface area is preferably greater than 5 m/g, chemical Species. Some research Suggests that an average more preferably greater than 10 m/g, even more preferably pore size in the range of 5 to 20 nm is leSS Susceptible to pore greater than 15 m/g and most preferably greater than 30 plugging. (Ghosh-Dastidar, A.; Mahuli, S. K.; Agnihotri, R.; m/g. Fan, L. -S. Investigation of High Reactivity Calcium Car bonate Sorbent for Enhanced SO Removal. Ind. Eng. Chem. 0222. The pore volume of the powders generated by Res., 1996, 35 (2), 598). Also, the chemical species gas can Spray processing methods according to the present invention only penetrate a thin (about 0.1 um) shell of the solid (the intermediate compounds, or the final absorbent com absorbent particle during repeated absorption and desorption positions Such as calcium carbonate or calcium oxide) is cycles, which is less than one-tenth of the normal particle preferably greater than about 0.01 cm/g, more preferably size. Reactive absorbents present in natural and conven greater than about 0.04 cm/g and even more preferably tional materials generally have a large particle size, low greater than about 0.15 cm/g. In one embodiment, the pore porosity and do not have a three-dimensional pore network volume is from about 0.05 cm/g to about 0.30 cm/g. As is discussed above, the pore Volume of the absorbent material Structure. powder can be increased by including a pore enhancing 0218. According to one embodiment of the present inven agent in the precursor composition. Further, the absorbent tion, the microStructure of the absorbent particles is con compound can preferably absorb a chemical Species to form trolled to enable mass transport of the reactants and products a reacted absorbent compound where the pore Volume of the to and from the Surface of the powder during contaminant reacted compound is not less than 70% of the pore volume removal and regeneration and to retain the beneficial micro of the absorbent compound, more preferably is not less than Structure throughout multiple cycles. The absorbent particles 80% of the pore volume of the absorbent compound and according to this embodiment are produced by Spray pro even more preferably is not less than 90% of the pore cessing, which enables tight control over the chemical volume of the absorbent compound. composition and microStructure of the materials. 0223 Spray processing enables control over the powder 0219. The powder batch produced by spray processing batch characteristics in the following manner. The particle according to one embodiment of the invention includes Size and spread of the particle size distribution is controlled Substantially spherical aggregates of Smaller primary par by controlling the size and Size distribution of the droplets ticles. This particle structure is illustrated in FIG. 7. The produced by the droplet generator because each individual Spherical aggregates may have different sizes and spread of droplet becomes an individual particle. The Size and size Size distribution that can be controlled by Spray processing. distribution of the particles in the powder batch is controlled The microStructure of the aggregates can also be controlled independent of the chemical composition of the powder. by the Spray processing to control the Surface area, crystal Furthermore, the microStructure, composition and crystal linity, Size and porosity within each aggregate. The aggre linity of the particles and the Sub-particles that comprise the gate microStructure, average size and spread of the size primary particles are controlled by the nature of the precur distribution can be controlled to provide the optimum per Sors that are used to produce the droplets and the processing formance in a given application depending on the operating parameters (especially the temperature/time history) of the and regeneration parameters. particles in the gas phase during Spray processing. As a result, the powder batch produced by Spray processing, 0220. In another embodiment of the invention, the Sub whether directly used to produce pellets or powder coatings, Stantially Spherical particles are composite particles that or used after post processing Subsequent to the Spray pro have controlled composition and morphology (FIG. 8). For cessing Step, can have a controlled microStructure at a example, the particles can include various ratios of CaO and number of different length scales. The size and size distri MgO or Al-O as is illustrated in FIG. 8, with other metals bution of the particles produced by Spray processing can be or metal oxides present to achieve desired absorption prop varied to control the pore size and size distribution between erties, Such as enhanced absorption kinetics at various the aggregates (inter-aggregate porosity, FIG. 7). temperature ranges. The role of inert additives (e.g., inert at the temperature(s) at which the absorption occurs), Such as 0224. The pore sizes of the inter-aggregate pores will MgO or Al-O, is to aid the recyclability of the absorbent typically be in the micron size range and therefore classified containing powders by minimizing the Sintering and loss of as macroporosity. In one embodiment of the present inven Surface area and pore Volume. The Sintering inhibition tion, the aggregates are composed of finer Sub-particles of characteristics of these additives may be derived from the the absorbent material that have been aggregated through the composite nature of the microstructure and/or from the use Spray processing method. The finer Sub-particles are derived of dopant ions in the absorbent material lattice. The dso either from Soluble precursors or Suspensions of particulate average particle Size of the powders generated by Spray precursors. The preferred size of the Smaller primary par US 2005/0230659 A1 Oct. 20, 2005 ticles is not greater than about 500 nm, more preferably not greater than about 300 nm and even more preferably not TABLE 3-continued greater than about 100 nm. The primary particles are pref erably at least about 10 nm, such as at least about 30 nm in Density Volume size. As a result, the size of the pores formed between the Compound (g/cc) (cc/mol) primary particles in the aggregate are in a similar Size range Ba(NO), 3.24 81 (about 30 nm to 1000 nm) and are classified as mesoporos BaCO 2.66 85 ity. Finally, the primary particles can range from being fully crystalline (i.e., single crystal) to being amorphous. Single crystal Sub-particles are likely to be fully dense and exhibit 0228. According to one embodiment of the present inven no further porosity, but amorphous particles can include tion, the porosity of the absorbent powder batch is controlled pores that are classified as microporosity. In another embodi at the microporosity, mesoporosity and macroporosity Scales ment of the present invention, the absorbent particles are to reduce the loSS of Surface area and pore Volume and composite particles of various amorphous or crystalline maintain a high activity over a large number of regeneration metal oxides. cycles. In one embodiment of the present invention, the aggregate particles formed by the Spray processing method 0225. The correct combination of macroporosity, meso have a controlled inter-aggregate porosity (i.e., porosity porosity and microporosity will depend on the composition between the aggregates) as well as intra-aggregate porosity of the material, the conditions under which it is used to react (i.e., porosity within the aggregates). It would normally be with the species to be absorbed and the conditions under expected that the inter-aggregate pores (micron size) are which the de-activated absorbent is re-activated. The impor larger than the intraaggregate pores (nanometer size). tance of this aspect of the invention can be clarified further 0229. In some cases, the absorbent compound reacts with by reference to specific materials. Table 2 lists the density of the chemical Species to be removed on the Surface of the a number of relevant Ca-based compositions and the calcu absorbent compounds and forms a passivating layer, which lated volume per mol of fully dense material. limits the further reaction of underlying absorbent. AS a TABLE 2 result, the mass activity of the absorbent is relatively low Density Volume and once the Surface of the absorbent has reacted with the Compound (g/cc) (cc/mol) chemical Species, no further reaction can occur. One way to CaO 3.25 17 improve the mass activity according to the present invention CaCOs 2.71 37 is to disperse the absorbent on, or form a composite with, a CaS 2.5 29 relatively high Surface area Support, which is passive or inert CaCO 2.2 67 (i.e., does not Substantially react) with the chemical species at the reaction temperature. A representation of this embodi ment is illustrated in FIG. 9, where the spray-processed 0226. The density of the CaS and CaCO is lower than Spherical agglomerates include Sub-particles of Support that of CaO. As a result, given that the molar mass of material with an absorbent Supported/dispersed over the calcium is constant through the removal of H2S and CO and surface of the sub-particles. The methods for controlling the the reactivation of the CaS and/or CaCO (Equations 1-4 and microStructure and morphology of the absorbent powder, as 5-9, respectively), the Volume will increase on conversion of described above, can also be applied to the Supported the CaO to CaS and/or CaCO. Therefore, this volume absorbent. The structure of the Supported absorbent material increase is likely to remove Some of the porosity imparted to can be in the form of a coating around the Support particles the original CaO powder. Regeneration of CaO from CaS or as a composite with interpenetrating Support and absor and/or CaCO will result in a decrease in volume of the bent material networkS. absorbent, but the pore structure formed as a result of the 0230. There are a number of advantages in accordance regeneration of CaO could be significantly different relative with this embodiment of the invention. The mass activity of to the starting CaO. This is typically the problem with the absorbent is significantly higher compared to the Situa existing CaO powder made by conventional routes because tion where an unsupported absorbent is used, assuming that the majority of the reactivity is derived from the high surface the Surface of the unsupported absorbent passivates. This area of Small particles and/or the presence of a roughened can enable the use of more exotic or expensive absorbent Surface. After Several regeneration cycles, the Surfaces materials, because a relatively Small mass of absorbent can become Smooth and/or the Small particles tend to Sinter, be dispersed over the surface of or inter-mixed with a leading to a reduction in Surface area and pore Volume, and relatively inexpensive Support Such as Silica (SiO2) or alu a reduction in reactivity. mina (AlO·). The presence of inert Support materials can 0227 Table 3 lists the density of a number of relevant also isolate and prevent Sintering of the absorbent com barium compounds and the calculated density and Volume of pound, particularly during multiple temperature Swings and a fully dense material. cycles. A further advantage is that the Support does not Substantially react with the chemical Species and there is no TABLE 3 change in the Volume or density of the Support framework. AS a result, the microstructure of the powder does not Density Volume change Significantly and a relatively high Surface area can be Compound (g/cc) (cc/mol) preserved over a large number of regeneration cycles. The BaO 5.72 27 Specific microStructure of the Supported or composite absor BacOs 4.43 44 bent will depend upon the Specific reaction needs. For example, a relatively thin coating of a highly reactive US 2005/0230659 A1 Oct. 20, 2005 Supported absorbent may have eXtremely good Selectivity CaS and/or CaCO, rather than only CaO. After the powder and reactivity to remove low levels of gas Species at a batch including CaS and/or CaCO is pelletized or coated relatively high Space Velocity. However, the capacity of the onto a surface, the CaS and/or CaCO is treated to form CaO absorbent bed will be relatively low due to the relatively low having a high level of porosity. Controlling the microstruc mass of absorbent present compared to a thicker coating. AS ture of the CaS and/or CaCO powder batch establishes the a result, a larger bed may be required to increase the total Specific microstructure, Surface area and porosity in the capacity of the absorbent. Alternatively, a thicker absorbent System with a combination of composition (addition of inert coating on an inert Support or a composite particle with additives) and processing conditions (choosing correct spray interpenetrating networks of absorbent and inert materials conversion and post processing conditions) for the absorbent may require lower Space Velocities, but the capacity of the material. When CaO is formed from CaS and/or CaCO in bed will be higher. However, there may also be situations in the first step, because CaS and CaCO have a lower density which nano-composite Structures comprise relatively thick than CaO, the surface area and porosity of the CaO batch absorbent layers that enable high Space Velocities. will decrease to a lesser extent relative to the CaS and/or CaCO, batch from which it is derived if a beneficial starting 0231. According to another embodiment of the present porosity Structure is achieved in the initial intermediate invention, the Spherical aggregate particles consist of a compound. mixture of two types of Sub-particles; nanosized reactive absorbent materials Such as Group 1 or Group 2 metal oxides 0234. Other materials with a low density can be selected and Sub-particles of inert additives Such as nanosized alu as the intermediate compound. Referring to Table 2, CaCO mina particles. When Spherical aggregate particles are has a lower density than CaS and CaCO. Therefore CaCO mixed with a binder and other reagents in the process of can be used as an intermediate material to establish the formation of extrudates, pellets or monoliths, the Spherical microStructure, porosity, aggregate size and size distribution aggregate Structure is destroyed, leaving the nanosized reac of the powder batch. A wide variety of other materials can tive sub-particles uniformly distributed throughout the struc also be used, in particular inorganic and metal-organic ture within the core structure of the binder network. The compounds which are Soluble in water or other Solvents Such binder network insures that the formed structure has the that they can be employed in Spray processing. necessary Strength, while the reactive absorbent particulates are combined within the porosity of the formed material. 0235. This embodiment of the present invention is illus The porosity of the formed material is such that when the trated in FIG. 10. In the first step, after forming the pellet or reactive absorbent particulates convert to the lower density depositing the powder coating including the low density reactive compound (such as carbonates or Sulfites) their material, the powder batch is heated to form the activated Volume does not exceed the core Volume of the pores that absorbent in a form that has a higher Surface area and they are located within. This insures that the formed struc porosity compared to the Starting material. The powder tures that reactive absorbent particulates can undergo mul batch can be heated either before pelletizing, extruding or tiple cycles of carbonation/decarbonation (for the case of coating by post-processing of the intermediate compound CaO and CO2 absorption for example) without destroying powder, and/or after pelletizing, extruding or coating the the structure of the binding network of the formed structure intermediate powder onto a Support. The absorbent material and insuring that the formed Structure will remain Substan is then used to remove the chemical Species and is eventually tially intact throughout multiple cycles. Saturated by the chemical Species and can no longer absorb appreciable amounts of the chemical Species. The Saturated 0232. According to another embodiment of the present absorbent will have the pore distribution and microstructure invention, the absorbent materials (e.g., CaO) are fabricated capable of Sustaining multiple generation cycles without from an intermediate compound having a lower density, Significant loSS of Surface area, porosity or Structural integ Such as CaCO and CaCO. Decomposition of these inter rity. mediate compounds into the absorbent compound will alter the microstructure of the intermediate compound, but in a 0236. The reversible reaction with a chemical species controlled way, and will therefore lead to an increased such as HS, CO or NO is less likely to close porosity and Surface area in the absorbent compound as compared to reduce the Surface area of an absorbent powder obtained by conventional preparation methods. In addition, the Spray direct Spray processing or Spray processing followed by processing method for making either the intermediate com post-processing through the Sequential decomposition of a pound or the final absorbent compound introduces addi lower density material as compared to designing the micro tional levels of meso- and micro-porosity and therefore a Structure around the absorbent compound. Another aspect of this embodiment of the present invention involves the Specific microstructure which is unattainable with conven execution of Sequential chemical reactions involving Spe tional preparation methods. cific reagents and pore forming chemicals performed by 0233 According to this embodiment, the microstructural Spray processing to produce discrete particles comprising changes to the absorbent that occur during regeneration Specific compositions and microStructures that are con cycles is reduced by Starting with a powder batch that Structed in a logical design Sequence. This aspect of the includes an intermediate compound that has a density simi present invention is illustrated in FIGS. 2 and 4. lar to or less than that of the reacted absorbent, but which itself is a precursor to form the absorbent compound. The 0237 Specifically, FIG. 2 illustrates a case where the goal is to establish the microstructure of the powder using a chemical reactions in the individual particles occur in the low density intermediate compound to avoid sintering of the following Sequence: particles and a reduction in Surface area and porosity. One approach is to produce the reacted material as the interme 2NH,(NO.)SNH).co-cacolor (14) diate powder batch, for example a powder batch including US 2005/0230659 A1 Oct. 20, 2005 CaCOcs CaCO3(+COs (16) a Supported low density precursor to an absorbent. For CaCOse CaO +COs (17) example, in the case where the powder batch is pelletized, one of the phases can be Selected to create a structural 0238 Leading to the overall chemical reaction: Support Such that during active use and regeneration, the pellets retain their structural integrity. For example, the SeaSt.-Colo CaO+CO+CO2+ (18) Support on which the intermediate compound or the absor 0239. By carrying out this reaction in a stepwise fashion bent compound is dispersed can be an active material with in the gas phase, the microstructure can be fabricated in a respect to peptization during pellet formation to form a Stepwise fashion. This ability does not exist in a Single three-dimensional Support network. In addition, one or more Solid-State or liquid phase powder manufacturing Step. catalytically active materials may be incorporated into the Structure to achieve a catalytic function in addition to a gas 0240 The precursors and reagents are preferably selected absorption function. to achieve the foregoing reaction Sequence. Calcium nitrate, Ca(NO), is one preferred precursor for CaO in spray 0244. According to one embodiment of the present inven processing methods Such as spray pyrolysis and Spray con tion, the absorbent material, which includes the absorbent version. In this reaction Sequence the evaporation of water compound, can include a Second component that does not occurs quickly, on the order of milliseconds, while the whole undergo a reaction with the absorbed species, Such as MgO, gas phase material processing Sequence takes place on the Al-O or SiO. Dolomite is a naturally existing material order of Seconds. Therefore, the majority of the reactions in comprised of CaCO and MgCO. However, natural dolo this sequence are Solid-state reactions. Ca(NO) reacts with mite has fairly low initial Surface area and comprises only (NH4)2(CO) according to the reaction of Equation 13 to about 50 wt.% CaCO and therefore the initial absorption form CaCO. The reaction rate can be Suppressed at room capacity is significantly reduced and the change in micro temperature using a correctly formulated (pH adjusted) Structure on carbonation/decarbonation cycles leads to rapid Solution. loSS of Surface area and porosity. The presence of MgO in processed natural dolomite does introduce Some advanta 0241 According to another embodiment, the reaction can geous water gas shift capability to the material, which may be controlled in a way that a colloidal dispersion of CaCO be advantageous for Some applications. particulates is formed where the size of the CaCO particles is from about 50 nanometers to 500 nanometers, more 0245 According to one embodiment of the present inven preferably from about 30 nanometers to about 300 nanom tion, the recyclability of the absorbent compound, Such as eters and even more preferably from about 30 nanometers to CaO, can be improved by integrating the absorbent with about 100 nanometers. The colloidal suspension of CaCO additional materials. Such as Al-O, MgO, TiO2 or SiO2 to particulates can then be spray processed to form aggregate form composite particles. For Some applications, aluminum particles of the particulates. oxides and magnesium oxides are particularly preferred. For example, the introduction of Soluble reagents Such as 0242 CaCO has a low solubility in water and thermally Mg(NO), in the starting precursor Solution will result in the decomposes before it melts, SO the reaction can occur in the formation of a tailored dolomite-like composition. Introduc Solution phase as the droplets enter the reactor and the tion of nanophase particulate Al-O will result in the for microStructure of the resulting CaCO product is preserved. mation of a CaO/Al2O composite. The composition of the The NHNO that is formed acts as a pore forming reagent intermediate compound, as well as for the final absorbent and thermally decomposes at a temperature higher than the powder, is important Since it determines the absorption temperature at which CaCO is formed, but lower than the capacity and recyclability of the absorbent. For example, decomposition temperature of CaCO, thus introducing low amounts of an inert additive (alumina, titania, Silica or porosity. CaCO is known to thermally decompose first to MgO) may lead to absorbent materials that have high CaCO (at about 500° C) and then to CaO (at about 750 Sorption capacity Since the amount of CaO will be high. C.). Therefore, in this sequence, the microstructure and However, these high Sorption capacity materials may not porosity designed into the Solid-State product is first con have enough resistance to Sintering and may be Susceptible Structed around CaCO, the material with the highest molar to rapid decrease of Surface area and porosity, and, therefore, volume, and then transferred to CaCO and ultimately to have low activity after multiple cycles. The amount of inert CaO through post-processing Steps. The crucial aspect of additive, therefore, is generally not greater than 50 wt.% of this reaction Scheme is that the reactions occur Sequentially, the total absorbent powder, such as from about 1 wt.% to Separated by both time in the reactor as well as the tem about 50 wt.%. Preferably, the inert additive is present at a perature at different locations in the reactor while Substan level of not greater than 25 wt.% of the total absorbent tially retaining the microStructure at both the nanometer powder, such as from about 5 wt.% to about 25 wt.% and Scale and micrometer Scale. If the same reagents are pro even more preferably not greater than 15 wt.% of the total cessed by conventional Solution and/or Solid-State proceSS absorbent powder. ing, the microstructure cannot be tailored acroSS this wide variety of length Scales in discrete particles. 0246 The composite absorbent material, such as one which includes an absorbent compound and an inert com 0243 It is worth noting that the foregoing embodiments pound, has a high absorption capacity. In one embodiment, can be employed in any variation or combination to achieve the absorbent compound contained within the absorbent excellent reactivity and the ability to go through multiple material preferably has an absorption capacity of at least regeneration cycles (recyclability). For example, the ability about 30 mol. 9%, more preferably at least about 40 mol. %, to control the microStructure, morphology, aggregate size even more preferably at least about 60 mol. 9% and even and aggregate size distribution within an absorbent powder more preferably at least about 90 mol. %. In another batch can be combined with a supported absorbent or with embodiment, the absorption capacity of a CO2 absorbent is US 2005/0230659 A1 Oct. 20, 2005 at least about 10 grams CO2/100 grams of unreacted absor 0250) The recycle time is dictated by the size of the bent material, more preferably at least about 20grams CO, absorbent bed, the number of beds present and the rate at and even more preferably, at least about 30 grams CO2 per which the chemical species is absorbed and desorbed. Based 100 grams of unreacted absorbent material. The absorption on the initial Studies of Ca-based materials and the thermo capacity can be maintained over many cycles, Such as at dynamics among CaO, CO and CaCOs, it has been deter least 10 cycles, more preferably at least 50 cycles, even more mined that CO absorption has a relatively high rate at a preferably at least 100 cycles and even more preferably at lower temperature compared to CO desorption, as least about 200 cycles and even more preferably at least expected. Through the formation of an optimum microstruc about 500 cycles. ture, the formation of an impervious layer on the active absorbent can be reduced, which is known to limit the 0247 Reaction Rate Enhancement absorption rate after all exposed Surfaces of the active absorbent have reacted. 0248. The reactivity of the individual active sites in the absorbent compound is dictated by the chemical composi 0251 The more difficult problem to solve is achieving tion and crystalline Structure of the absorbent compound as desorption kinetics that are Sufficiently rapid that the des well as by the reaction conditions during manufacture of the orption Step does not limit the recycle time. Increasing the absorbent compound. The chemical composition can influ temperature can increase the rate constant for the desorption ence the activity for a Specific reaction with a gas Species by reaction, but this may lead to Some Sintering of the material adjusting the electronic and Steric nature of the activity of and reduce the cycle life. Therefore, alternative Strategies the Surface reaction Sites. For example, the presence of a need to be employed to minimize the time required for dopant can enhance the reactivity compared to the material desorption. without a dopant. Steric effects may enhance the reactivity 0252) The microstructure of the absorbent bed can affect by having atoms present which distort the Surface Structure the rate of desorption. An increase in the rate of desorption to make the active sites more Sterically accessible for has been observed as the particle Size of absorbent material reaction with the compound Species. The reactivity of the powderS is decreased. Since the Size of the absorbent par absorbent is also strongly influenced by its crystalline Struc ticles is not Small enough to introduce changes in the ture, and Surface defects are also known to enhance the Strength of the chemical bonds (i.e., the particles are pref reactivity of the Surfaces. Different crystal faces of a crys erably not below a quantum confinement limit of about 30 talline material also have different reactivities and crystal nm), these observations most probably reflect a change in line materials with more reactive crystallographic planes the powder microStructure leading to an improvement in the exposed on the Surface will result in a higher overall activity diffusion transport characteristics of the material. However, of the absorbent. In Some cases amorphous (non-crystalline) the microStructure according to the present invention can be materials are more reactive than crystalline materials. Amor further optimized to improve the kinetics of the reaction phous materials can also have greater capacities for absorp provided the feature size of the changes are at or below a tion than crystalline materials because they can more easily crystallographic length scale of 30 nm (i.e., to create Surface accommodate the absorbed Species in their disordered Struc ture. The size of the individual amorphous or crystalline tension and Surface pressure effects). particles can also be important due to the Strain when very 0253) According to one embodiment of the present inven Small particles or crystallites are present, especially below tion, a metal oxide absorbent compound lattice Structure can about 50 nm in size. be doped with elements that lead to an enhancement of the kinetics of the desorption reaction. The dopants can be 0249. The number of active sites is also important to the Selected from divalent ions, preferably from the group overall activity of the absorbent compound. The total num consisting of Mg, Ni, Fe, Zn, Co and Cu. Preferably, the ber of active sites normally correlates with the content of the dopants are present at a level of at least about 0.1 at. 76 and absorbent compound and the Surface area of the absorbent not greater than about 10 at. 96, such as from about 1 at. % material. An absorbent that has a higher Surface area will to about 5 at. 76 expressed as a percentage of the total have a higher number of active sites. The total activity of the absorbent compound. These dopants can also lead to an material, often defined by its mass activity or Specific enhancement of the rate of absorption by the absorbent. activity, is the product of the number of active sites and their Therefore, it is preferred that the changes in the absorbent individual activity. Therefore, the surface area of two composition do not lead to an increase in the rate of Samples of the same material may be similar, but because the desorption at the expense of Significantly decreasing the rate reactivity of the respective active sites in each material is of absorption and therefore to change the rate-limiting Step, different, the total reactivity is different. Also, some active such as being limited by the fuel feed rate of the surface Sites may be disposed in pore channels that are too Small to reaction. be reached by the contaminant Species. Indeed, it is possible to have an absorbent compound that has a lower Surface area 0254. Accordingly, high performance absorbents can be relative to another Sample of the same material, but that has fabricated by Spray processing to form alkali metal oxide a higher overall activity. This is why in the design of (e.g., Group 1 metal oxides), alkaline earth metal oxide (e.g., absorbent materials, other factorS Such as pore Volume and Group 2 metal oxides), ZnO-based absorbents and others pore size distribution, Surface composition and crystallinity that have varying amounts of divalent ions, have a Smaller of the phases are as important as the Surface area with ionic radius compared to the metal element (e.g., Ca") and respect to achieving high overall absorption capacity. In are electropositive So that the presence of Such a hetero atom addition, the ability of the absorbent structure to retain its in the compound structure will change the physiochemical pore Structure and Surface composition after multiple cycles properties of crystal Structure by altering the bond distance is critical to its use as a reversible absorbent. and electronic structure owing to the difference of ion US 2005/0230659 A1 Oct. 20, 2005 potential (Z/r) between the metal ion and the dopant ion(s). hollow rings Similar to macaroni. AS the ribbon of slurry Accordingly, Mg, Ni, Fe, Zn, Co and Cucations are pre emerges from the hole, it begins to dry and harden Suffi ferred, provided that the doped absorbent materials have a ciently to maintain its shape. The extruder can be equipped crystal structure Similar to the metal oxide (e.g., an isomet with a slicing device, So that the ribbon is either cut into ric-hexoctahedra Structure for CaO and/or a trigonal-rhom prescribed lengths by the knife rotating outside the end plate bohedral Structure, for dolomite, akimotoite and ankerite or simply allowed to break up as it falls onto a moving belt with a composition of (MNP)COs, where M, N and Pare on its way to the dryer. the divalent or higher Valency metal cations other than Ca, 0261) Extruding equipment can be classed in one of two Such as Mg, Fe or Si and where x, y, Z are the molar fraction categories: press extruders and Screw extruders. PreSS of total metal ions). extruders are used principally for pastes that are Viscous, 0255 Regeneration of Sample Performance during Sys whereas Screw extruders are preferred for thixotropic prod tem Operation ucts. The ease of extrusion and quality of the product depend on the following properties of the paste: 0256 During reversible absorption of a chemical species, the microstructure of the absorbent material particles can 0262) 1. Viscosity (adhesivity): A non-thixotropic change over long periods of time at elevated temperature product that is too viscous will block the extruder. A and/or after a large number of cycles. This can lead to a product that lacks in Viscosity cannot be extruded decrease in the absorption capacity of the material. The with a Screw and will give extrudates without absorption capacity can be restored by the treatment of the mechanical resistance when extruded by a press. material with reagents that re-establish the pore Structure of 0263. 2. Thixotropy (fluidity): Certain substances the material. One Such reagent that can increase the capacity become leSS Viscous under Shearing forces, and then of the absorbent material after it has been reduced is water. recover their initial state after the forces have been Treatment of the absorbent with water above room tempera released for a time called the relaxation time. The ture increases the capacity of the material for future cycles. existence of Such thixotropic properties is eminently This treatment can be applied multiple times to prolong the favorable for the flow of a paste and formation of a material lifetime (i.e., the capacity and number of cycles of Solid granule at the exit of a die, providing the the material). While not wishing to be bound by any theory, relaxation time is short enough. it is believed that the performance improvement is likely due to a sintering of the material at the nanosize level. In the case 0264 3. Stability: Under extrusion conditions, there of CaO, it is likely that the surface area is reduced over time should be no dynamic Sedimentation of the product through chemical rearrangement and formation of Ca-O- through exuding water and forming a paste that is too Cabonds, possibly via formation of Ca-OH intermediates, Viscous. removing previously accessible pores. The reaction of the 0265. 4. Homogeneity: The paste must be homoge Strained Ca-O-Cabonds with water or a similar reagent, neous to assure that the quality of the product is regenerates Ca-OH bonds which on absorption re-estab constant. When necessary, the paste is homogenized lishes the previous structure. in a mixer-kneader under controlled conditions of 0257). Other reagents that may be suitable to regenerate temperature, time, and pH. An exceSS of kneading the Surface area and recyclability of these materials, includ can in fact compact the material and Suppress poten ing protic reagents Such as methanol, organic acids and tial macropores. Screw extruders partially knead the inorganic acids. It will be appreciated that the absorbent paste as it travels along the Screw. materials of the present invention can be implemented in a 0266 Even for a given charge with specific properties, variety of Systems. For example, the materials can be used the operating variables are rather poorly defined and are in a fluidized bed, fixed bed, moving bed or variations closely related to the type of equipment. Generally they thereof, or Similar reactor configuration. The following include: mixing time, water content, adhesives content, described Several preferred modes of implementation. paste aging and extrusion temperature. In the case that a powder does not have certain level of fluidity or plasticity, 0258 Formation of Reactor Bed: Pelletization various additives can be used to aid the pre-forming of 0259 Extrusion is the most economic and commonly pastes or microgranules, Such as: applied Shaping technique for the formation of absorbent pellets according to the present invention. For extrusion, the 0267 1. Lubricants for improving the rheological absorbent material powder is generally in the form of a wet behavior, Such as liquid (water, mineral oil) or Solid paste or a powder that is converted to a wet paste within the (starch or clays like montmorillonite, Stearic acid, extrusion machine. The extrusion machine forces the paste and various Stearates); through a die and cuts the extruded material at the desired 0268 2. Binders (aluminas or clays). Binders are length. The detailed process is described below. added to also increase the post-compression adhe 0260 A slurry of absorbent powder is fed from a hopper Sion, as for example Starch is added for palletizing/ into a Screw drive. Peptizing agents, Such as nitric acid or extrusion of active carbon; other organic acids Such as acetic acid, may be added to 0269. 3. Peptizing agents to deagglomerate the par deagglomerate the primary particles by lowering the Zeta ticles, Such as dilute acetic or nitric acid. By peptiz potential, improving the extrusion process. The Screw forces ing, an increase in the adhesive forces due to chemi the slurry through holes in the end plate. Usually circular in cal bonds resulting from contact between the pastes croSS Section, these holes can also be made in the shape of can be achieved, meanwhile the particle Surfaces are cogs or rings, ovals, Stars, three-lobed joined rings, or made more chemically reactive, and US 2005/0230659 A1 Oct. 20, 2005 22 0270. 4. Combustible materials to increase the as porous monoliths, porous membranes, honeycomb Struc porosity (the So-called pore-formers like carbon ture monoliths or corrugated Support Structures. These Sup black, graphite, talc, starch, etc.). port Structures are typically comprised of metals or metal oxides to aid in thermal Stability and in Some cases to 0271) If the extrusion is performed well, the particles improve thermal conductivity. (extrudates or pellets) formed are very regular, hard, and uniform. However, if the extrusion is uneven and the rate of 0277. In order to coat the Support structures, the powders extrusion from one section of the dies is different from that can be formed into a slurry, paste or ink that is applied to the of another Section, the particle length can be quite variable Support Surface. Methods to coat the powders described in and the hardneSS and sharpness of the ends can also be this invention onto the Surface of the Support Structures may variable. The extruder, however, can rapidly produce great include wash-coating, dipping, Screen printing, ink-jet print quantities of product of various shapes and as a consequence ing, Spraying or any other printing or coating, digital or is relatively inexpensive in comparison with pilling or analog technologies known to those skilled in the art. pelletizing. 0278 Formation of Reactor Bed: Textile, Cloth or Paper 0272. In practice, the particulate absorbents have to be Support pelletized to meet certain crush Strength. Pelletization of 0279 While the advantage of the coated structures is that powders typically involves reaction of the powders to be the Space Velocity of the System can be increased, one pelletized with a binder and extrusion of the paste through potential limitation of the coated Structures is a reduction in a die to give the desired pellet geometries. In the case of capacity. In order to achieve a better compromise between catalysts and gas absorbent materials, the binder System is the capacity and Space Velocity characteristics of coated typically Al-O combined with a peptizing agent Such as an Structures and pellets, the absorbent materials described organic acid. On reaction, these materials yield a metal herein can be incorporated into porous cloths. The cloths organic compound that penetrates the entire Structure and on may be comprised of woven or non-woven fibers of a variety Subsequent thermal decomposition yields a continuous of different materials including various metals (for example, AlOs skeleton that provides mechanical Support. Ideally, the copper, nickel or stainless Steel), metal oxides or carbon extrudates will maintain the high reactivity and high cycle fibers. In a preferred embodiment, the powders are incor ability of the original powder after pelletizing. porated into a metal-based cloth to improve the thermal 0273. There are a number of approaches to pelletization. characteristics of the powder bed. One is directly pelletizing the original absorbent powders 0280. In order to coat the cloth structures, the powders (e.g., CaO) that show high reactivity to the chemical species are often formed into a slurry, paste or ink that is then to be absorbed (e.g., CO). Another is pelletizing an inter applied to the cloth surface. Methods to coat the powders mediate powder precursor (e.g., CaCO) with a certain onto the Surface of the cloth Structures may include wash amount of binder. After post-processing the decomposition coating, dipping, Screen printing, ink-jet printing, Spraying of the absorbent material will facilitate the formation of the or any other printing or coating, digital or analog technolo microStructure and porosity of the extrudates, and the obtained pellets will maintain or even improve the absorbent gies known to those skilled in the art. performance during absorption/desorption cycles. In this 0281. In another embodiment, the powders may be incor approach, however, the amount of binder used for extrusion porated into the bulk of the textile, cloth or paper at the time should be carefully considered to achieve maximum capac of manufacture of the textile, cloth or paper Support. In the ity for removal of the chemical Species being absorbed. typical paper or non-woven cloth manufacturing process, the powders are mixed with the fibers in the original Slurry and 0274. According to one embodiment, a pellet is formed as the Suspended materials are removed from the slurry, the that includes at least about 5 wt.% of a particulate inter powders are trapped inside the Structure of the material. mediate compound to an absorbent compound, more pref Post-processing may be necessary to achieve Some chemical erably at least about 35 wt.% and even more preferably at attachment between the particles and the Support to com least about 75 wt.%, where the particulate intermediate compound has a theoretical density that is not greater than pliment the mechanical entrapment within the pore Structure the theoretical density of the absorbent compound and created by the fibers. wherein the particulates are Substantially Spherical. The 0282. It will also be appreciated that the absorbent mate pellet can have a crush strength of at least about 1 N/mm. The rials can be formed into monoliths, Such as by extruding the pellet can include, for example, alumina as a binder. materials. 0275 Formation of Reactor Bed: Coated Structures 0283 Absorbent materials as part of membrane separa tion devices 0276 The pelletization of the materials described above is only one of a number of methods to create a reactor bed 0284. The reversible gas absorbent materials according to for absorption of a chemical Species from a fluid Stream. The the present invention can also be integrated into Structures advantages of a pelletized bed are that the capacity of the that allow for Separation of a chemical Species from a bed is relatively high. However, under Some circumstances, mixture of gases through the Selective absorption of the the operating Space Velocity of Such a pelletized reactor bed chemical Species with an absorbent material as part of a can limit the performance of the overall System. Therefore, Separation device. In one embodiment, the gas Separation according to another embodiment of the present invention, can be achieved by forming a dense Structure comprised of the materials can be coated onto a Surface that provides a the absorbent material, possibly combined with an inert high available Surface area for the powder. The Structures phase, that on one side of its Structure is exposed to a reagent that are typically coated are high Surface area Structures Such Stream that contains the target species (e.g., H2, NO, CO2, US 2005/0230659 A1 Oct. 20, 2005 23 H2S) that is to be separated. The target chemical species are 0288 High absorption capacity can be achieved over 50 absorbed by the active material and are transported through cycles, over 100 cycles, over 200 cycles and even over 500 the body of the Separation device driven by a gradient cycles. According to one embodiment, the absorbent mate (typically in concentration or pressure) to another region of rial retains at least about 10 grams of CO per 100 grams the Separation device where the target Species is released. AS unreacted absorbent compound after each of the cycles. an example, the Separation device may take the form of a More preferably, the absorbent material retains at least 20 thin disk comprising the absorbent material mixed with an grams CO2 per 100 grams unreacted absorbent compound inert Species Such as alumina in a way that the disk is not after each of the cycles, even more preferably at least about permeable to all gases. One face of the disk or membrane is 30 grams CO2 per 100 grams unreacted absorbent compound exposed to a gas Stream that contains CO as the target after each of the cycles, even more preferably at least about species to be removed. The active absorbent (which may 40 grams CO2 per 100 grams unreacted absorbent compound need to be heated to an appropriate temperature) selectively after each of the cycles and even more preferably at least 50 absorbs the CO to form CaCO. On the opposite face of the grams CO2 per 100 grams unreacted absorbent compound membrane, a vacuum can be applied to remove the CO2 as after each of the cycles. According to one embodiment, the it desorbs from the surface of the CaCO and reforms CaO. absorbent material can be cycled at least 50 times wherein The membrane may also be comprised of the active absor the absorbent material retains at least about 20 mol.% of its bent embedded into an organic membrane material Such as theoretical absorption capacity after each cycle. More pref an organic polymer. These membranes can be used under erably, the absorbent material retains at least about 30 mol. different conditions to remove target molecules from liquid % of its theoretical absorption capacity, even more prefer or gaseous fluids. ably at least about 50 mol. 9% and even more preferably at 0285) The absorbent materials of the present invention least about 70 mol. 76. can be regenerated by desorption of the absorbent to com 0289. According to one embodiment, the absorbent mate plete the cycle. Regeneration of the absorbent can include rial can preferably retain at least about 15 grams CO2 per heating the absorbent to an elevated temperature. The pre 100 grams unreacted absorbent material after each of 50 ferred regeneration temperature depends upon the absorbent cycles, even more preferably at least about 25 grams CO2 compound and the chemical Species that is absorbed. For per 100 grams unreacted absorbent material after each of 50 example, for the regeneration of CaO from CaCO, a cycles, even more preferably -at least about 35 grams CO preferred temperature is at least about 700° C. and prefer per 100 grams unreacted absorbent material after each of 50 ably does not exceed about 900 C., at ambient pressure. It cycles, and even more preferably at least about 50 grams will be appreciated that the regeneration temperature and/or CO, per 100 grams of unreacted absorbent material after regeneration time for Some absorbent materials can be each 50 cycles. Further, the absorbent material can be cycled decreased in many applications by reducing the pressure at least 100 times when the absorbent material retains at least over the material. about 20 mol. 9% of its theoretical CO absorption capacity. 0286 According to the present invention, the absorbent 0290 According to one embodiment, the absorbent mate material can be cycled (i.e., absorbing the chemical species rial includes composite particles that includes an absorbent to a minimum capacity and then regenerating to remove compound and an inert compound Such as a metal oxide. The substantially all of the chemically bound absorbed species) absorbent material preferably has a high absorption. The at least ten times, wherein the absorbent compound retains absorbent compound contained within the composite absor at least about 40 mol.% of its theoretical absorption capacity bent material preferably has an absorption capacity of at based on the quantity of absorbent compound present in the least about 30 mol. 9% after 100 cycles, more preferably at absorbent material for every cycle through at least ten least about 50 mol. % and even more preferably at least cycles. Further, the absorbent compound can preferably about 70 mol. 9%. According to one embodiment, the absor retain at least about 50 mol. 9% of its theoretical absorption bent material has an absorption capacity of at least about 10 capacity for every cycle up to ten cycles and more preferably grams CO2 per 100 grams of absorbent material after 100 at least about 60 mol.% of its theoretical absorption capacity cycles, preferably at least about 20 grams CO and more for every cycle up to ten cycles. According to certain preferably at least about 30 grams CO per 100 grams of preferred embodiments of this aspect of the present inven absorbent material. tion, the absorbent can retain at least about 30 mol.% of its theoretical absorption capacity for every cycle up to 100 0291. It is also an advantage of the present invention that the absorbent does not undergo large fluctuations in bulk cycles, more preferably up to 200 cycles and even more density over numerous cycles. The bulk density of the preferably up to 500 cycles. In one embodiment, the absor materials described in the present specification is defined as bent is cycled at least 200 times and the absorbent retains at the mass of the particles divided by the Volume they occupy, least about 10% of its theoretical absorption capacity, more including the pore Spaces between the particles. This volume preferably at least about 25% of its theoretical absorption includes the Solid material Volume, the open and closed pore capacity and even more preferably at least about 50% of its Volume within the particles, as well as the interparticle Void theoretical absorption capacity after 200 cycles. volume. The bulk density of the material is typically derived 0287. The absorbent materials according to the present from a mercury porosimetry measurement. For example, invention also have a high initial absorption capacity for the according to one embodiment, the absorbent material is chemical Species. According to one embodiment, the initial formed into a pellet having a first bulk density. The pellet absorption capacity (expressed as a mole fraction of the can then be used Substantially as described above and the absorbent compound present in the absorbent material) is at pelletized absorbent will react upon absorption of the chemi least about 60 mol.%, and even more preferably is at least cal Species to form a reacted absorbent pellet having a about 90 mol %. Second bulk density. After the pellet is regenerated back to US 2005/0230659 A1 Oct. 20, 2005 24 the absorbent material, it will have a third bulk density. vegetables. The absorbent materials can also be used in Using commercially available absorbent materials, the Sec breathing apparatus Such as a diving re-breather. The mate ond bulk density is much lower than the first bulk density rials can also be used to remove carbon dioxide from a gas and the third bulk density would be similar to the first bulk Stream Such as those resulting from the combustion of fossil density. According to the present invention, however, the fuels. The materials can also be used to remove CO from Second bulk density is not significantly different than the H-containing gas (e.g., Syngas) from a reforming process. first bulk density and the third bulk density is much higher See, for example, U.S. Pat. No. 6,280,503 by Mayorga et al., than the first bulk density. According to one embodiment, which is incorporated herein by reference in its entirety. the third bulk density is preferably greater than 100% of the first bulk density, such as up to about 140% of the first bulk 0299 NO. Abatement density. 0300. The present invention can be applied to the absorp tion of nitrogen oxides (NO), Such as from a gas Stream. 0292 HS Absorption Materials that are useful for absorption of NO, according to 0293. The present invention can be applied to absorbent the present invention include the oxides, hydroxides or materials for the absorption of H2S, Such as from a gas carbonates of alkali metals, alkaline earth metals and lan Stream resulting from coal combustion. Useful absorbent thanide metals. Preferred among these are the oxides, compounds for absorption of H2S according to the present hydroxides or carbonates of Sodium (Na), potassium (K), invention include CaO and ZnO. calcium (Ca) or barium (Ba) that are either unsupported or 0294. According to one embodiment of the present inven Supported by porous inert Substrates, Such as Al-O. Mixed tion, a metal Sulfide may be formed directly—that is, the oxides, such as MnO:ZrO or BaO:CuO are also useful. microStructure of the absorbent material can be designed Other useful materials include Y-Ba-Cu-O oxides and around the absorbent in its “sulfur-absorbed form” and prior CeO2, Such as CeO2:ZrO composites and perovskites Such to being used for Sulfur absorption, it is activated. The as BaSnO. Other materials can include Fe-O dispersed on activation Step is a step that converts the metal Sulfide to a microporous carbon. metal oxide, for example by reaction of the meal sulfide with 0301 NO absorption materials are particularly useful for water at elevated temperature to liberate H2S. The advantage treating a gas Stream, Such as from coal combustion, to of producing the metal Sulfide is that the microStructure is remove nitrogen oxides. The Spray processing method of the fixed around the Sulfur-absorbing material in its lowest present invention enables the fabrication of the foregoing density form or highest molar volume form. In this situation NO, absorption materials with controlled porosity character the porosity and Surface area of the active Sulfur absorbent istics and controlled chemistry and morphological charac is likely to be higher than the metal sulfide around which the teristics to enable high Storage capacity (close to theoretical) microStructure is determined which aids in the reproducible and good absorption/desorption properties, and controlled uptake of HS. In this embodiment, the metal sulfide can be reduction to N with the incorporation of the appropriate produced directly by the Spray-based processing method catalyst in the multi-functional Sorbent. through use of reagents that employ Sulfur-containing 0302) These metal oxides can be produced using spray reagents Such as Soluble or colloidal inorganic (e.g., metal processing routes from a variety of different precursors. In nitrate) metal-organic (e.g., metal carboxylate) or organo one embodiment of this invention, a Solution comprising metallic (e.g., metal alkyl) compounds with Sulfur-contain Soluble precursorS Such as metal nitrates can be used. In ing reagents Such as HS, RS (R=alkyl group) or thiocar another embodiment, a colloidal dispersion can be used. boxylates. Alternatively, the metal Sulfides may also be Such a colloidal dispersion is typically comprised of Sus produced by reacting intermediate metal precursors or metal pended particles of either the metal oxide or a precursor to oxides with Sulfur containing reagents in a post-processing the metal oxide Such as a metal organic compound, includ Step that follows the Spray processing Step. ing but not limited to a metal carboxylate or oxalate. The 0295). In each of the cases described above, the materials colloidal dispersion can be formed by dispersion of pre produced might also contain inert material (that is material formed particles or by generating the particles in-situ by for that does not substantially react with HS) that is present to example reacting one or more Soluble precursors to form an act as a dispersant or Support of the active Sulfur absorbent insoluble, colloidal precursor. An example of the latter route to help maintain the microstructure and therefore the absorp is the reaction between calcium nitrate and ammonium tion capacity of the Sulfur absorbent on repeated Sulfur oxalate to form a colloidal Suspension of calcium oxalate. In absorbent cycles. another embodiment of this invention, a precursor may be produced by a spray-based route and Subsequently converted 0296 CO. Abatement to the final material in a separate processing Step Such as 0297. The CO absorbent materials according to the thermal reaction of an intermediate. present invention are useful in a number of applications. Some applications will require the regeneration (decarbon 0303. In yet another embodiment of the present inven ation) of the carbonated compound, whereas others will not tion, the metal nitrate may be formed directly—that is, the require this cycling Step. microStructure of the material is designed around the absor bent in its “NO-absorbed form” and prior to being used for 0298 Specifically, the absorbent materials of the present NO absorption, it is activated. The activation Step is a step invention can be used in anesthesiology applications and that converts the metal nitrate to a metal oxide or carbonate, applications that require the removal of carbon dioxide from for example by reaction of the metal nitrate with air at an enclosed space, Such as Space vehicles and Submarines. elevated temperature to form either the metal oxide or the The absorbent materials can also be used in the food industry metal carbonate. The advantage of producing the metal Such as the packaging of foods including respiring fruits and nitrate is that the microStructure is fixed around the Sulfur US 2005/0230659 A1 Oct. 20, 2005 25 absorbing material in its lowest density or highest molar Sion of calcium oxalate. In another embodiment of the Volume form. In this situation, the porosity and Surface area present invention, a precursor may be produced by a Spray of the active NO absorbent is likely to be higher than the based route and Subsequently converted to the final material metal nitrate around which the microstructure is determined in a separate processing Step Such as the thermal reaction of which aids in the reproducible uptake of NO. In this an intermediate. embodiment, the metal nitrate can be produced directly by 0310. It should be realized that in each of the cases the Spray processing method through use of reagents that described above, the materials produced might also include employ metal nitrate reagents Such as Soluble or colloidal an inert material (a material that does not Substantially react inorganic Species. Alternatively, the metal nitrates may also with H) that acts as a dispersant or Support for the active H be produced by reacting intermediate metal precursors or absorbent to help maintain the microstructure and therefore metal oxides with NO containing reagents in a post-pro the absorption capacity of the H absorbent on repeated cessing Step that follows the Spray manufacturing Step. cycles. 0304. It should be realized that in each of the cases 0311. Other H absorption materials that are useful for described above, the materials produced might also contain hydrogen Storage include metal hydrides, Such as hydrides inert material (that is material that does not Substantially of Mg, B, Al, Li, Na, or complexes thereof, including react with NO) that is present to act as a dispersant or NaAlH4, MgH, LiH, Mg(BH), Al(BH), HBNH, support of the active NOabsorbent to help maintain the NaBH, AlH, LiAlH, LiBH and Mg(AlH). Also useful microStructure and therefore the absorption capacity of the is Mg2NiH, which forms 2H and a Mg2Nialloy. Compared NO absorbent on repeated NO absorption cycles. to the lower H Storage capacity (<2 wt.%) of misch metal 0305 Reversible Hydrogen Storage hydrides like LaNis, Mg-Ni, MgFe and TiFe, the complex metal hydrides generally have a large H. Storage capacity 0306 The present invention can also be applied to fab because of their light formula weight and a higher number ricate materials for the Storage of hydrogen (H). Safe and of hydrogen atoms Surrounding the metal atom. For economical means for hydrogen Storage and delivery a key examples, LiBH has a theorectical hydrogen mass of 18.3 component for the widespread application of electrochemi wt.%, and it is reported that the reversible hydrogen mass cal devices using hydrogen as a reactant, Such as fuel cells. is 13.4 wt.%. LiH has a reversible hydrogen mass of about Hydrogen Storage materials are described, for example, in 9.0 wt.% and NaAlH has a reversible hydrogen mass of U.S. Patent Application Publication No. 2002/0096048 by about 5.5 wt.%. Even with the addition of a heavy element Cooper et al., which is incorporated herein by reference in into the metal hydride, the hydrogen mass is still acceptable. its entirety. However, current H Storage materials have a One example is Mg2FeH, which has the potential for 5.5 low absorption and desorption rate and the particles have a wt.% hydrogen Storage. tendency to break down after multiple cycles. 0312 Although the foregoing metal hydrides show a high 0307 According to the present invention, hydrogen can capacity for hydrogen Storage, there are a lot of challenges be reversibly stored in an absorption material that is fabri in practical use; the rates of hydrogen absorption and cated by Spray processing. According to one embodiment, desorption are slow; the temperature for hydrogen desorp the absorption material can include a misch metal, prefer tion is high and the material breaks down into Small particles ably Selected from the group consisting of LaNis, Mg-Ni, after multiple cycling. The Shortcomings of current available Mg2Fe, TiFe, and ZrMn. Such materials form metal metal hydrides as hydrogen Storage materials could come hydrides upon reaction with H, Such as LaNishes. These from lack of either technologies or Strategies that enable the materials are particularly preferred for use in Ni-metal Selective tailoring of material composition and microstruc hydride batteries. ture. For example, the low porosity and large particle size 0308 These misch metal hydrides can be produced using like NaBH are responsible for slow H absorption and Spray processing routes from a variety of different precur desorption. The Strong binding between hydrogen atom and Sors in a number of different Strategies. In one Strategy the metal hydride results in the higher temperature for desorp misch metal hydride can be produced directly using Spray tion. based processing in a reducing atmosphere to form the final 0313. In one embodiment of the present invention, the product. In another Strategy, a precursor to the misch metal aforementioned chemical hydrides can be formed by Spray hydride can be produced, e.g., in an oxidized form, which is processing of Soluble precursors, Such as organic Solvent converted to the final misch metal hydride or alloy in a soluble NaBH, with or without an inert filler to help control Second processing Step. In this case, a metal oxide may be the pore Structure of the material on reversible absorption of formed as an intermediate, which on Subsequent thermal H. A catalytic component Such as Ti, Cr, V, Mn, Fe can also reduction forms the misch metal alloy or hydride. be included in the metal hydride solution to improve the kinetics of hydrogen absorption and desorption. These mate 0309. In one embodiment of the present invention, a rials may also be formed in-situ by the reaction of different Solution comprising precursors that are Soluble in the pre reagents that are either dissolved or Suspended in the pre cursor Solution Such as metal hydrates can be used. In cursor Solution and converted to a chemical hydride on Spray another embodiment, a colloidal dispersion of metal processing. hydrates can be used. The colloidal dispersion can be formed by dispersion of pre-formed particles or by generating the 0314. In another embodiment of the present invention, an particles in-situ by for example reacting one or more Soluble intermediate compound to the final chemical hydride may be precursors to form an insoluble, colloidal precursor. An produced by Spray processing, Such as a metal alloy, a example of the latter route is the reaction between calcium molecular metal-containing compound, a metal-containing nitrate and ammonium oxalate to form a colloidal Suspen complex or a metal-containing material (metal oxide, US 2005/0230659 A1 Oct. 20, 2005 26 nitride, halide, Sulfide or the like) which can be converted to Example L-1 the chemical hydride on Subsequent processing by either 0322 This example illustrates the production of a 50 g thermal or reducing treatments. batch of LiO absorbent according to the present invention 0315. It should be realized that in each of the cases by spray pyrolysis. 114 g of Li-nitrate (LiNO)) is dissolved described above, the materials produced can also include an in 447 g of de-ionized water. 1 g of lactic acid and 1g of inert material (that is material that does not Substantially NH-nitrate (NHNO) is added while stirring and the react with H) that is present to act as a dispersant or Support Solution is stirred for 10 minutes. Spray pyrolysis is con of the active Habsorbent to help maintain the microstruc ducted on an ultraSonic transducer System at a furnace ture, and therefore the absorption capacity of the H absor temperature of 1100° C., with air as both the carrier gas and bent on repeated H2 absorbent cycles. the quench gas at 60 SLPM and 5 SCFM, respectively. The 0316 Alkali metal nitrides are also useful as hydrogen reaction residence time of the System is 1.5 Seconds, as Storage materials and can be fabricated in accordance with calculated by the quotient of the System Volume and the the present invention. Microporous carbon-based materials carrier gas flow rate corrected for temperature expansion. that contain metal catalyst nanoparticles can also have The collected powder batch consists essentially of LiO enhanced hydrogen Storage characteristics. Example L-2 0317. Another material that is useful for the reversible 0323 This example illustrates the fabrication of a 500 g absorption of H is a carbon-based material, including car batch of 10%. Al-O/LiO according to the present invention bon powders, carbon fibers, graphite, Vitreous carbon, car in a spray dryer. 1.03 kg of Li-nitrate is dissolved in 5.8 kg bon aerogels and Surface modified carbon materials that of de-ionized water and 2.23 kg of NH-oxalate typically also comprise other materials. Such as catalysts for ((NH)2CO) is dissolved in 5.8 kg of de-ionized water. The the oxidation and reduction of H. Spray-based routes to the two solutions are individually mixed on shear mixers for 30 these materials can be used to disperse the catalytically minutes. The Li-nitrate solution is slowly added to the active phase over the Surface of the carbon. The use of Spray NH-Oxalate Solution while shearing to precipitate LiCO. processing for this purpose has been described in U.S. Pat. The resulting 10 wt.% solids dispersion of precipitated No. 6,103,393, which is incorporated herein by reference in LiCO, is sheared for an additional hour. 0.25 kg of DIS its entirety. In each of the cases described above, the PAL 23N4-20 (a 20% boehmite alumina dispersion in water, materials produced can also include an inert material that is available from Sasol, North America) is added, followed by present to act as a dispersant or Support of the active H. 15 minutes of shear mixing. The precursor dispersion is fed absorbent to help maintain the microstructure and therefore into a mixed-flow Spray dryer at a liquid feed rate to the absorption capacity of the H absorbent on repeated H2 maintain inlet/outlet temperatures of 975 F/580 F., using absorbent cycles. a two-fluid nozzle with an air pressure of 65 psig. The 0318. The spray processing method of the present inven residence time of the System is 10 Seconds, as calculated tion enables the fabrication of the foregoing hydrogen above. The powder is collected using a cyclone. Storage materials with controlled porosity characteristics and controlled chemistry and morphological characteristics Example L-3 to enable high Storage capacity (close to theoretical) and 0324. This example illustrates the fabrication of a good absorption/desorption properties. The particles can be LiCOs/Al2Os composite by spray drying and post-process formed with a controlled particle size and high porosity, ing according to the present invention. 140 g of a powder which will enable hydrogen Storage materials to show higher consisting of 10%. Al-O is put into 2 quartz boats, which are Storage capacity and faster adsorption kinetics. Controlled then loaded into a tube furnace. Under flowing air, the doping of a component into the Structure of the metal furnace is ramped 10 C./min to 500 C., held for 3 hours hydride can lower the affinity of the metal to the hydrogen and is then cooled to room temperature. The resulting atom, decreasing their binding energy. A catalytic compo powder consists essentially of LiCO and Al-O. nent can also be added on the Surface of the metal hydride, which will more readily dissociate the hydrogen molecules Example L-4 into hydrogen atom during absorption. The hydrogen Stor age materials manufactured through the Spray processing 0325 This example illustrates the fabrication of a powder method of the present invention can have a high Storage batch consisting essentially of LiCO and LiO with Al-O capacity, faster kinetics, physical Strength, and durable by Spray drying and post-processing according to the present recycle ability. invention. 140 g of a powder consisting 10%. Al-O made by spray drying (Example L-3) is put into 2 quartz boats, which EXAMPLES are then loaded into a tube furnace. Under flowing air, the 03.19. The following examples illustrate the production furnace is ramped 10 C./min to 800° C., held for 3 hrs and and application of absorbent materials according to the is then cooled to room temperature. The resulting powder present invention. consists essentially of a mixture of LiCO, Li2O and Al-O. 0320 The absorbent materials according to the present 0326 Examples H-5 to H-7 illustrate the fabrication of invention can be fabricated by Spray pyrolysis or Spray hydrogen Storage materials according to the present inven drying, and either fabrication method can be followed by tion. post-processing. The following Specific examples illustrate Some of these non-limiting embodiments. Example H-5 0321 Examples L-1 to L-4 illustrate the fabrication of 0327. This example illustrates the production of a 5 g lithium-based absorbent materials. batch of LiAlH4 absorbent according to the present inven US 2005/0230659 A1 Oct. 20, 2005 27 tion by Spray processing. 5 g of commercially available invention using a spray dryer. 1.84 kg of Ca-nitrate is LiAlH, (around 10-40 mesh) is dissolved in 50 g of diethyl dissolved in 2 kg of de-ionized water and 1.11 kg of ether and the solution is stirred for 1 hr under an N NH-oxalate is dissolved in 4.5 kg of de-ionized water. The atmosphere. Spray processing is conducted on an ultraSonic two solutions are individually mixed on shear mixers for 30 transducer system at a furnace temperature of 150° C., with minutes. The Ca-nitrate solution is slowly added to the pure N as both the carrier gas and the quench gas at 60 NH-oxalate solution while shearing. The resulting 10 wt.% SLPM and 5 SCFM, respectively. The reaction residence Solids dispersion of precipitated Ca-Oxalate is sheared for an time of the System is 1.5 Seconds, as calculated by the additional hour. The precursor dispersion is fed into a quotient of the System Volume and the carrier gas flow rate mixed-flow Spray dryer at a liquid feed rate to maintain corrected for temperature expansion. The collected powder inlet/outlet temperatures of 975° F/580° F (524° C./304° batch consists essentially of fine powder C.), using a two-fluid nozzle with an air pressure of 65 psig. The residence time of the System is 10 Seconds as calculated Example H-6 by the quotient of the System Volume and the gas flow rate 0328. This example illustrates the production of a log corrected for expansion using the outlet temperature. The batch of LiH/AlH absorbent according to the present inven powder is collected using a cyclone. The powder batch tion by Spray processing. 7.8 g of commercially available consists essentially of CaCO. AlH (around 10-40 mesh) and 2.2 g of commercially available LiH (10-40mesh) is dissolved in 100 g of diethyl Example A-3 ether solution and the solution is stirred for 1hr under an N 0332 This example illustrates the fabrication of a 1 kg atmosphere. 1 g of MCI, (where M=Ti, Cr, V, Mn, Fe) is batch of CaCO and 5% Al-O according to the present added into the solution, followed by 30min of shear mixing. invention in a Spray dryer. 1.74 kg of Ca-nitrate is dissolved Spray pyrolysis is conducted on an ultraSonic transducer in 2 kg of de-ionized water and 1.06 kg of NH-oxalate system at a furnace temperature of 150 C., with pure N as ((NH)2CO) is dissolved in 5 kg of de-ionized water. The both the carrier gas and the quench gas at 60 SLPM and 5 two solutions are individually mixed on shear mixers for 30 SCFM, respectively. The reaction residence time of the minutes. The Ca-nitrate solution is slowly added to the System is 1.5 Seconds, as calculated by the quotient of the NH-Oxalate Solution while shearing to precipitate CaCO. System Volume and the carrier gas flow rate corrected for The resulting 10 wt.% solids dispersion of precipitated temperature expansion. The collected powder batch consists CaCO, is sheared for an additional hour. 0.25 kg of DISPAL essentially of fine powder 23N4-20 (a 20% boehmite alumina dispersion in water, Example H-7 available from Sasol, North America) is added, followed by 0329. This example illustrates the production of a 10 g 15 minutes of shear mixing. The precursor dispersion is fed batch of NaAlH4 absorbent according to the present inven into a mixed-flow Spray dryer at a liquid feed rate to tion by Spray processing. 10 g of commercially available maintain inlet/outlet temperatures of 975 F/580 F., using NaAlH, (around 10-40 mesh) is dissolved in 100g of diethyl a two-fluid nozzle with an air pressure of 65 psig. The ether solution and the solution is stirred for 1 hr under an N residence time of the System is 10 Seconds, as calculated atmosphere. 2 g of MCl (where M=Ti, Cr, V, Mn, Fe) is above. The powder is collected using a cyclone. The powder added into the solution, followed by 30min of shear mixing. batch consists essentially of 5 wt.% Al-O and 95 wt.% Spray pyrolysis is conducted on an ultraSonic transducer CaCO. system at a furnace temperature of 150 C., with pure N as both the carrier gas and the quench gas at 60 SLPM and 5 Example A-3A SCFM, respectively. The reaction residence time of the 0333. This example illustrates the fabrication of a powder System is 1.5 Seconds, as calculated by the quotient of the batch consisting essentially of CaCO with 25% Al-O. System Volume and the carrier gas flow rate corrected for 1.38 kg of Ca-nitrate is dissolved in 2 kg of de-ionized water. temperature expansion. The collected powder batch consists 0.84 kg of NH-oxalate is dissolved in 5 kg of de-ionized essentially of fine powder water. The two Solutions are mixed on shear mixers indi Example A-1 vidually for 30 minutes. The Ca-nitrate solution is slowly added to the NH-oxalate solution while shearing. The 0330. This example illustrates the production of a 5 g resulting 10 wt.% Solids dispersion of precipitated Ca batch of Ca-oxide (CaO) absorbent according to the present oxalate is sheared for an additional hour. 1.25 kg of DISPAL invention by spray pyrolysis. 21 g of Ca-nitrate (Ca(NO)) 23N4-20 is added, followed by 15 minutes of shear mixing. is dissolved in 178 g of de-ionized water. 1 g of lactic acid The precursor dispersion is fed into a mixed flow Spray dryer and 1g of NH-nitrate (NHANO) is added while stirring and at a liquid feed rate to maintain inlet/outlet temperatures of the solution is stirred for 10 minutes. Spray pyrolysis is 975/580 F., using a two-fluid nozzle with an air pressure of conducted on an ultraSonic transducer System at a furnace 65 psig. The residence time of the System is 10 Seconds, S temperature of 900 C., with air as both the carrier gas and defined above. The powder is collected using a cyclone and the quench gas at 60 SLPM and 5 SCFM, respectively. The consists essentially of CaCO and Al-O. reaction residence time of the System is 1.5 Seconds, as calculated by the quotient of the System Volume and the Example A-4 carrier gas flow rate corrected for temperature expansion. The collected powder batch consists essentially of CaO. 0334) This example illustrates the fabrication of a CaCO / Al-O composite by Spray drying and post-processing Example A-2 according to the present invention. 140 g of a powder 0331. This example illustrates the fabrication of a 1 kg consisting essentially of CaCO and 5% Al-O (Example batch of Ca-oxalate (CaCO) according to the present A-3) is put into 2 quartz boats, which are then loaded into US 2005/0230659 A1 Oct. 20, 2005 28 a tube furnace. Under flowing air, the furnace is ramped 10 ration at a rate of 112 SCFH. The elongated tube is set with C./min to 500 C., held for 3 hours and is then cooled to an angle and rotational rate in order to yield a residence time room temperature. The resulting powder consists essentially of 24 minutes. of CaCO and Al-O. Example A-5 Example A-9 0335 This example illustrates the fabrication of a powder 0339. This example illustrates the fabrication of a 3 kg batch consisting essentially of CaCO and CaO with Al-O powder batch consisting essentially of CaCO:MgCO by Spray drying and post-processing according to the present (with a calculated CaO:MgO wit. ratio of 80:20). Individu invention. 140 g of a powder consisting essentially of ally, 4.24 kg of Ca-nitrate is dissolved in 5 kg of de-ionized CaCO, and 5% Al-O, made by spray drying (Example A-3) water, 4.11 kg of NH-oxalate is dissolved in 6 kg of is put into 2 quartz boats, which are then loaded into a tube de-ionized water, 1.6 kg of Mg-nitrate is dissolved in 2 kg furnace. Under flowing air, the furnace is ramped 10 C./min to 750 C., held for 3 hrs and is then cooled to room of de-ionized water and 1.43 kg of NH-oxalate is dissolved temperature. The resulting powder consists essentially of a in 5 kg of de-ionized water. These Solutions are shear mixed mixture of CaCO, CaO and Al-O. for 30 minutes. Separately, the nitrate Solutions are added to the oxalate Solutions. The two resulting dispersions of Example A-6 Ca-Oxalate and Mg-Oxalate are sheared Separately for 1 hour 0336. This example illustrates the fabrication of a 500 g then combined. The resulting 10 wt.% solids dispersion of batch of a powder consisting essentially of CaCO, MgCO, precipitated Ca-Oxalate and Mg-Oxalate is sheared for an with a calculated CaO:MgO wit. ratio of 50:50 according to additional hour. The precursor dispersion is fed into a the present invention. Individually, 0.92 kg of Ca-nitrate is mixed-flow Spray dryer at a liquid feed rate to maintain dissolved in 1.0 kg of de-ionized water, 0.54 kg of NH inlet/outlet temperatures of 975 F/580 F., using a two-fluid oxalate is dissolved in 2.5 kg of de-ionized water, 1.0 kg of nozzle with an air pressure of 65 psig. The residence time of Mg-nitrate (Mg(NO)) is dissolved in 1.0 kg of de-ionized the System used is 10 Seconds, as calculated above. The water, and 0.56 kg of NH-oxalate is dissolved in 1.8 kg of powder is collected using a cyclone and consists essentially de-ionized water. These Solutions are shear mixed for 30 of CaCO:MgCO. minutes. Separately, the nitrate Solutions are added to the oxalate Solutions. The two resulting dispersions of Ca oxalate and Mg-oxalate are sheared separately for 1 hour Example A-10 and are then combined. The resulting 10 wt. % solids 0340 This example illustrates the fabrication of a powder dispersion of precipitated Ca-Oxalates and Mg-Oxalates is Sheared for an additional hour. The precursor dispersion is batch consisting essentially of a mixture of CaCO and fed into a mixed-flow Spray dryer at a liquid feed rate to CaO:MgO by Spray drying and post-processing according to maintain inlet/outlet temperatures of 975 F/580 F., using the present invention. 200 g of a powder consisting essen a two-fluid nozzle with an air pressure of 65 psig. The tially of CaCO:MgCO (calculated CaO:MgO wit. ratio of residence time of the System used is 10 Seconds, as defined 80:20, Example A-9) is put into shallow pans, which are then above. The powder is collected using a cyclone and consists loaded into a convection oven. Under flowing air, the essentially of CaCO:MgCO. furnace is ramped 10 C./min to 500 C., held for 3 hrs and is then cooled to room temperature. The resulting powder Example A-7 batch consists of a mixture of CaCO and CaO:MgO. 0337 This example illustrates the fabrication of a powder batch consisting of a mixture of CaCO and CaO:MgO by Example A-11 Spray drying and post-processing according to the present invention. 320 g of a CaCO:MgCO powder made on a 0341 This example illustrates the fabrication of a mix spray dryer and with a calculated CaO:MgO wit. ratio of ture of CaCO and CaO:MgO by spray drying and post 50:50 (Example A-6) is put into shallow pans, which are processing according to the present invention. 200 g of then loaded into a convection oven. Under flowing air, the CaCO, MgC.O. (80:20 ratio, Example A-9) is put into furnace is ramped 10° C./min to 500 C., held for 3 hours, shallow pans, which are then loaded into a convection oven. and is then cooled to room temperature. The resulting Under flowing air, the furnace is ramped 10 C./min to 750 powder batch consists essentially of CaCO and CaO:MgO. C., held for 3 hrs and is then cooled to room temperature. Example A-8 0342 Table 4 lists the particle size distribution (PSD), 0338. This example illustrates the fabrication of a powder BET Surface area, average pore diameter and pore Volume batch consisting essentially of 95 wt.% CaCO and CaO for select absorbent examples listed above. For the examples with 5 wt.%. Al-O by Spray drying and post-processing in Table 4 and the following examples herein, the PSD is according to the present invention. A powder batch consist measured by laser light Scattering, Such as in a ing essentially of CaCO and 5% Al2O, (which is made the MICROTRAC instrument (Microtrac, Inc., Montgomer same method as Example A-3), is put into a screw feeder and yville, Pa.). The BET surface area is measured by nitrogen delivered to a rotary calciner comprising an elongated tube adsorption and the average pore diameter is measured by at a rate of 1 kg/hr. The tube includes three equal-length BJH adsorption. The pore volume is measured by nitrogen heating Zones that are set to 450° C., 750° C. and 750° C. adsorption and is the pore Volume only of pores having a respectively. Air is delivered in a counter-current configu diameter of not greater than about 100 nanometers. US 2005/0230659 A1 Oct. 20, 2005 29 TABLE 4 TABLE 6-continued Average Composition PSD Pore Pore (nominal, expressed d10, d50, d90 BET Surface Diameter Volume Example as oxides) Precursor Method Example (um) Area (m/g) (nm) (cm/g) A-20 CaO:MgO Example A-19 PP at 500° C. A-2 2.0, 5.0, 13.0 19.6 10.6 O.O517 (90:10 by wt.) for 3 hrs A-3 2.3, 5.7, 16.0 24.5 16.5 O.1O1 A-21 CaO:MgO Ca-nitrate/NH- SD A-4 1.7, 4.4, 11.7 17.7 13.1 O.O58 (90:10 by wt.) oxalate A-5 3.7, 10.3, 25.0 18.9 12.5 O.O59 5% Al-O. Mg-nitrate/NH A-6 1.3, 3.0, 6.0 24.2 13.9 O.084 oxalate A-7 3.1, 6.7, 14.3 60.1 16.1 O.242 DISPAL 23N4-2O A-8 5.5, 14.8, 26.8 N/A N/A N/A A-22 CaO:MgO Example A-21 PP at 500° C. A-10 N/A 27.8 13.4 O.O93 (90:10 by wt.) for 3 hrs 5% Al-O. A-23 CaO:MgO Ca-nitrate/Mg- SP (50:50 by at. 96) nitrate glycine 0343. The foregoing examples illustrate several different lactic acid fabrication methods for absorbent materials according to the A-24 CaO:MgO Ca-nitrate/Mg- SP (50:50 by at. 96) nitrate urea present invention. A number of additional examples are ethanol prepared in a Similar fashion and these additional examples A-25 CaO:MgO Ca-nitrate/Mg- SP are Summarized in Table 5. Table 5 lists absorbent materials (50:50 by at. 96) nitrate glycine that are obtained by different Spray processing methods, ethanol including spray pyrolysis (SP), and spray drying (SD) with A-26 CaO:MgO Ca-nitrate/Mg- SP (50:50 by at. 96) nitrate post-processing (PP). Examples A-12 and A-13 are post A-27 CaO Ca-nitrate SD processed powders from the foregoing Example A-2. 43 wt.% AIO NH-Oxalate Sample CaO1 is a commercial grade CaO (available from Al2O J.T. Baker, Phillipsburg, N.J., USA) that is also listed for A-28 CaO Example A-27 PP at 500° C. comparison. 43 wt.% Al-O. for 3 hrs TABLE 5 0345 The additives to the precursor compositions in Example Final Composition Precursor Method Examples A-23, A-24 and A-25 (namely glycine, lactic acid, A-12 CaO, CaCOs Example A-2 PP at 500° C. urea and ethanol) are porosity-enhancing agents for the for 3 hrs purpose of introducing additional porosity into the absorbent A-13 CaO, CaCOs Example A-2 PP at 750° C. materials. for 3 hrs A-14 CaO Ca-nitrate SP at 90O. C. 0346 FIG. 11 compares the particle size distribution NH-nitrate (do, dso and doo) of commercial grade CaO, CaO prepared Lactic acid A-15 CaO Ca-nitrate SP at 90O. C. by Spray pyrolysis and CaO/Al2O powders prepared by NH-nitrate Spray conversion of oxalate precursors in a spray dryer and A-16 CaO Ca-nitrate SP at 1.OOO C. post-processing of the intermediate compound. While the 20% NH-nitrate d, of the commercial CaO powder (CaO1) is approximately 2.5% PVP (10 k) 30 um, the do of CaO powder made by spray pyrolysis CaO1 CaO Commercial Grade NAA (Example A-16) is less than 10 um and for the Ca-oxalate intermediate compound (Example A-2) is about 5 um. 0344) Table 6 Summarizes additional absorbent examples 0347 Post-processing of Example A-2 at 750° C. to including CaO with MgO and/or Al-O that are prepared by convert it to CaO (Example A-13) increases the do from various spray processing methods according to the present about 5um to about 20 um, while the addition of Al-O as invention. an additive and post-processing at 750° C. (Example A-5) reduces the Sintering and do increases to only about 10 um. TABLE 6 The addition of other inert additives such as MgO has a Composition similar effect. (nominal, expressed 0348 FIG. 12 compares the BET surface area of the Example as Oxides) Precursor Method examples illustrated in FIG. 11. While the BET surface area A-17 CaO:MgO Ca-nitrate/NH- SD of the commercial CaO powder is less than 2 m/g, the (50:50 by wt.) Oxalate 5% Al-O. Mg-nitrate/NH Surface area of the absorbent materials prepared by Spray Oxalate processing according to the present invention is significantly DISPAL 23N4-2O higher. A-18 CaO:MgO Example A-17 PP at 500° C. (50:50 by wt.) for 3 hrs 0349 FIG. 13 compares the measured pore volume (for 5% Al-O. pores <100 nanometers) of the examples illustrated in FIGS. A-19 CaO:MgO Ca-nitrate/NH- SD (90:10 by wt.) Oxalate 11 and 12. The pore volume is less than 0.01 cm/g for the Mg-nitrate/NH conventional CaO powder and at least two times higher for Oxalate the absorbent powders prepared by Spray processing meth ods according to the present invention. The addition of inert US 2005/0230659 A1 Oct. 20, 2005 30 additive Such as alumina (e.g., Example A-3) can lead to an pressure of 65 psig. The residence time of the system is 10 even higher increase of the pore volume (e.g., up to 0.1 Seconds as defined above. The powder is collected using a cm/g). cyclone. 0350 Synthesis of ZnO-Based Absorbents Example Z-6 0351. The following Examples illustrate the fabrication of ZnO-based materials according to the present invention 0362 ZnO via Post-Processing by Spray drying, either with or without post-processing. 0363 600 g of ZnCO (PZL952602G) is put into alu minum trays, which is then loaded into a convection oven. Example Z-1 Under flowing air, the furnace is ramped 10 C./min to 300 0352 ZnO; 1 kg Batch C., held for 3 hrs, then cooled to room temperature. 0353 3.7 kg of Zn(NO)4HO (Zn-nitrate) is dissolved in 6.4 kg de-ionized water. The resulting 10 wt.% solids Example Z-7 Solution is fed into a mixed flow Spray dryer at a liquid feed 0364 ZnCO; 1 kg Batch rate to maintain inlet/outlet temperatures of 975/580 F., using a two-fluid nozzle with an air pressure of 65 psig. The 0365 2.4 kg of Zn(NO).4H2O is dissolved in 3.5 kg residence time of the System is 10 Seconds as calculated by de-ionized water, and 620 g (NH)2CO is dissolved in 3.5 the quotient of the System Volume and the gas flow rate kg of de-ionized water. The (NH)2CO, solution is slowly corrected for expansion using the outlet temperature. The added to the Zn(NO).4H2O solution while shearing. The powder is collected using a cyclone. resulting 10 wt.% Solids dispersion of precipitated Zn oxalate is sheared for an additional half hour. The precursor Example Z-2 dispersion is fed into a mixed flow Spray dryer at a liquid feed rate to maintain inlet/outlet temperatures of 975/580 0354 ZnO via Post-Processing F., using a two-fluid nozzle with an air pressure of 65 psig. 0355 600 g of ZnO is put into aluminum trays, which is The residence time of the system is 10 seconds as defined then loaded into a convection oven. Under flowing air, the above. The powder is collected using a cyclone. furnace is ramped 10 C./min to 300° C., held for 3 hrs, then cooled to room temperature. Example Z-8 Example Z-3 0366 ZnO via Post-Processing 0356 ZnO, 20% NHNO; 1 kg Batch 0367 600 g of ZnCO is put into aluminum trays, which 0357 3.6 kg of Zn(NO).4H2O is dissolved in 3 kg is then loaded into a convection oven. Under flowing air, the de-ionized water, and 200 g. NHNO (NH-nitrate) is dis furnace is ramped 10 C./min to 300° C., held for 3 hrs, then solved in 1 kg of de-ionized water. The NHNO solution is cooled to room temperature. added to the Zn(NO).4H2O solution with rapid stirring. 2.2 kg of de-ionized water is added to form a 10 wt.% solids Example Z-9 solution. The precursor Solution is fed into a mixed flow Spray dryer at a liquid feed rate to maintain inlet/outlet 0368 ZnO; 500 g Batch temperatures of 975/580 F., using a two-fluid nozzle with 0369 1.3 kg of Zn(CHO) (Zn-acetate) is dissolved in an air preSSure of 65 psig. The residence time of the System 3.6 kg de-ionized water. 50 g of lactic acid is added with is 10 seconds, as defined above. The powder is collected rapid stirring. The resulting 10 wt.% solids solution is fed using a cyclone. into a mixed flow Spray dryer at a liquid feed rate to maintain inlet/outlet temperatures of 975/580 F., using a two-fluid Example Z-4 nozzle with an air pressure of 65 psig. The residence time of the system is 10 seconds as defined above. The powder is 0358 ZnO via Post-Processing collected using a cyclone. 0359 600 g of ZnO is put into aluminum trays, which is then loaded into a convection oven. Under flowing air, the Example Z-10 furnace is ramped 10 C./min to 300° C., held for 3 hrs, then cooled to room temperature. 0370 ZnO via Post-Processing Example Z-5 0371 200 g of ZnCO is put into aluminum trays, which are then loaded into a convection oven. Under flowing air, 0360 ZnCO; 1 kg Batch the furnace is ramped 10 C./min to 300° C., held for 3 hrs, 0361) 1.9 kg of Zn(NO).4H2O is dissolved in 3.5 kg then cooled to room temperature. de-ionized water, and 930 g (NH)CO (NH-oxalate) is dissolved in 3.6 kg of de-ionized water. The (NH)2CO Example Z-11 solution is slowly added to the Zn(NO).4H2O solution 0372 ZnO via Post-Processing while shearing. The resulting 10 wt.% solids dispersion of precipitated Zn-oxalate is sheared for an additional half 0373 200 g of ZnCO is put into aluminum trays, which hour. The precursor dispersion is fed into a mixed flow Spray are then loaded into a convection oven. Under flowing air, dryer at a liquid feed rate to maintain inlet/outlet tempera the furnace is ramped 10 C./min to 500 C., held for 3 hrs, tures of 975/580 F., using a two-fluid nozzle with an air then cooled to room temperature. US 2005/0230659 A1 Oct. 20, 2005 Example Z-12 65 psig. The residence time of the System is 10 Seconds as defined above. The powder is collected using a cyclone. 0374 ZnCO; 500 g Batch 0375 720g of Zn(CHO) is dissolved in 2 kg de Example Z-18 ionized water, and 460 g (NH4)2C2O is dissolved in 1.8 kg 0386 ZnO, 15% Al-O via Post-Processing of de-ionized water. The (NH)CO Solution is slowly added to the Zn(CHO). Solution while shearing. The 0387 400 g of ZnO, 15% Al-O is put into aluminum resulting 10 wt.% Solids dispersion of precipitated Zn trays, which are then loaded into a convection oven. Under oxalate is sheared for an additional half hour. The precursor flowing air, the furnace is ramped 10 C./min to 300° C., dispersion is fed into a mixed flow Spray dryer at a liquid held for 3 hrs, then cooled to room temperature. feed rate to maintain inlet/outlet temperatures of 975/580 F., using a two-fluid nozzle with an air pressure of 65 pSig. Example Z-19 The residence time of the system is 10 seconds as defined 0388 ZnO, 15% Al-O; 500 g Batch above. The powder is collected using a cyclone. 0389) 1.1 kg of Zn(CHO) is dissolved in 3.5 kg Example Z-13 de-ionized water. 375g of DISPAL 23N4-20 is sheared into the Zn(CHO) solution. The resulting 10 wt.% solids 0376 ZnO via Post-Processing precursor Solution is fed into a mixed flow Spray dryer at a 0377 200g of ZnCO is put into aluminum trays, which liquid feed rate to maintain inlet/outlet temperatures of are then loaded into a convection oven. Under flowing air, 975/580 F., using a two-fluid nozzle with an air pressure of the furnace is ramped 10 C./min to 300° C., held for 3 hrs, 65 psig. The residence time of the System is 10 Seconds as then cooled to room temperature. defined above. The powder is collected using a cyclone. Example Z-14 Example Z-20 0378 ZnO via Post-Processing 0390 ZnO, 15% Al-O, 20% NHNO; 500 g Batch 0391) 1.1 kg of Zn(CHO) is dissolved in 3 kg de 0379 200 g of ZnCO is put into aluminum trays, which ionized water and 10 g of NHNO in 400 g of water. The are then loaded into a convection oven. Under flowing air, NHNO Solution is added to the Zn(CHO) solution, the furnace is ramped 10° C./min to 500 C., held for 3 hrs, then 375g of DISPAL 23N4-20 is sheared in. The resulting then cooled to room temperature. 10 wt.% solids precursor solution is fed into a mixed flow Spray dryer at a liquid feed rate to maintain inlet/outlet Example Z-15 temperatures of 975/580 F., using a two-fluid nozzle with 0380 ZnO, 15% Al-O; 500 g Batch an air pressure of 65 psig. The residence time of the System is 10 seconds as defined above. The powder is collected 0381 1.5 kg of Zn(NO).4H2O is dissolved in 2 kg using a cyclone. de-ionized water, and 550 g of Al(NO).9HO into 0.9 kg of water. The Al(NO) solution is added to the Example Z-21 Zn(NO),4HO Solution while shearing. The resulting 10 wt.% Solids precursor Solution is fed into a mixed flow Spray 0392 ZnO, 5% SiO; 500 g Batch dryer at a liquid feed rate to maintain inlet/outlet tempera 0393 1.7 kg of Zn(NO)4H2O is dissolved in 3.1 kg tures of 975/580 F., using a two-fluid nozzle with an air de-ionized water. 145 g of a Silica dispersion pressure of 65 psig. The residence time of the system is 10 (CABOSPERSE A2095, a fumed SiO, available from Cabot Seconds as defined above. The powder is collected using a Corp., Boston, Mass.) is sheared into the Zn(NO).4H2O cyclone. solution. The resulting 10 wt.% solids precursor Solution is fed into a mixed flow Spray dryer at a liquid feed rate to Example Z-16 maintain inlet/outlet temperatures of 975/580 F., using a 0382 ZnO, 15% Al-O via Post-Processing two-fluid nozzle with an air pressure of 65 psig. The residence time of the System is 10 Seconds as defined above. 0383 500 g of ZnO, 15% Al-O is put into aluminum The powder is collected using a cyclone. trays, which are then loaded into a convection oven. Under flowing air, the furnace is ramped 10 C./min to 300° C., Example Z-22 held for 3 hrs, then cooled to room temperature. 0394 ZnO, 5% SiO via Post-Processing Example Z-17 0395 400 g of ZnO, 5% SiO is put into aluminum trays, which are then loaded into a convection oven. Under flowing 0384 ZnO, 15% Al-O; 500 g Batch air, the furnace is ramped 10 C./min to 300° C., held for 3 0385) 1.5 kg of Zn(NO).4H2O is dissolved in 3 kg hrs, then cooled to room temperature. de-ionized water. 375g of an alumina dispersion (DISPAL 23N4-20, a 20% boehmite alumina dispersion in water Example Z-23 available from Sasol, North America) is sheared into the Zn(NO).4H2O solution. The resulting 10 wt.% solids 0396 ZnO, 10%. Al-O, 5% SiO; 500 g Batch precursor Solution is fed into a mixed flow Spray dryer at a 0397) 1.5 kg of Zn(NO)4H2O is dissolved in 3.1 kg liquid feed rate to maintain inlet/outlet temperatures of de-ionized water. 145g of CABOSPERSE A2095 and 250 975/580 F., using a two-fluid nozzle with an air pressure of g of DISPAL 23N4-20 is sheared into the Zn(NO).4H2O US 2005/0230659 A1 Oct. 20, 2005 32 solution. The resulting 10 wt.% solids precursor Solution is flowing air, the furnace is ramped 10 C./min to 300° C., fed into a mixed flow Spray dryer at a liquid feed rate to held for 3 hrs, then cooled to room temperature. maintain inlet/outlet temperatures of 975/580 F., using a two-fluid nozzle with an air pressure of 65 psig. The Example Z-30 residence time of the System is 10 Seconds as defined above. The powder is collected using a cyclone. 0410 ZnO:CaO:MgO (90:5:5) via Post-Processing Example Z-24 0411 175 g of ZnO:CaO:MgO is put into aluminum trays, which are then loaded into a convection oven. Under 0398 ZnO, 10%. Al-O, 5% SiO, via Post-Processing flowing air, the furnace is ramped 10 C./min to 500 C., 0399 400 g of ZnO, 5% SiO is put into aluminum trays, held for 3 hrs, then cooled to room temperature. which are then loaded into a convection oven. Under flowing air, the furnace is ramped 10 C./min to 300 C., held for 3 Example Z-31 hrs, then cooled to room temperature. 0412 ZnO:NiO (92.5:75); 500 g Batch Example Z-25 0413 1.2 kg of Zn(CHO) is dissolved in 2.6 kg 04.00 ZnO:AlO:MgO (80:10:10); 500 g Batch de-ionized water and 145g of Ni(NO) (Ni-nitrate) in 1 kg 0401 1.1 kg of Zn(CHO) is dissolved in 1 kg de of water. The Ni(NO) solution is added to the ionized water,370 g of Al(NO).9HO in 1 kg of water, and Zn(CH.O.). Solution while shearing. The resulting 10 wt. 320 g of Mg(NO)6H2O in 1 kg of water. The Al(NO) % Solids precursor Solution is fed into a mixed flow Spray Solution is added to the Zn(CHO). Solution while shear dryer at a liquid feed rate to maintain inlet/outlet tempera ing, followed by adding the Mg(NO) solution. The result tures of 975/580 F., using a two-fluid nozzle with an air ing 10 wt.% solids precursor Solution is fed into a mixed pressure of 65 psig. The residence time of the system is 10 flow Spray dryer at a liquid feed rate to maintain inlet/outlet Seconds as defined above. The powder is collected using a temperatures of 975/580 F., using a two-fluid nozzle with cyclone. an air preSSure of 65 psig. The residence time of the System is 10 seconds as defined above. The powder is collected Example Z-32 using a cyclone. 0414) ZnO:NiO (92.5:7.5) via Post-Processing Example Z-26 0415 200 g of ZnO:NiO is put into aluminum trays, 0402 ZnO:Al-O:MgO (80:10:10) via Post-Processing which are then loaded into a convection oven. Under flowing 0403 200 g of ZnO: AlO:MgO is put into aluminum air, the furnace is ramped 10 C./min to 300° C., held for 3 trays, which are then loaded into a convection oven. Under hrs, then cooled to room temperature. flowing air, the furnace is ramped 10 C./min to 300° C., held for 3 hrs, then cooled to room temperature. Example Z-33 Example Z-27 0416) ZnO:MgO:NiO (82.5:10:7.5); 500 g Batch 04.04 ZnO:Al-O:MgO (80:10:10) via Post-Processing 0417) 1.1 kg of Zn(CHO) is dissolved in 1.4 kg de-ionized water, 145g of Ni(NO) in 1 kg of water, and 04.05 200 g of ZnO: AlO:MgO is put into aluminum 315 g. Mg(NO) in 1 kg water. The Mg(NO) solution is trays, which are then loaded into a convection oven. Under added to the Zn(CHO) Solution while shearing followed flowing air, the furnace is ramped 10 C./min to 300° C., by the Ni(NO) solution. The resulting 10 wt.% solids held for 3 hrs, then cooled to room temperature. precursor Solution is fed into a mixed flow Spray dryer at a liquid feed rate to maintain inlet/outlet temperatures of Example Z-28 975/580 F., using a two-fluid nozzle with an air pressure of 0406 ZnO:CaO:MgO (90:5:5); 500 g Batch 65 psig. The residence time of the System is 10 Seconds as 0407 1.2 kg of Zn(CHO) is dissolved in 1 kg de defined above. The powder is collected using a cyclone. ionized water, 105 g of Ca(NO)4H2O in 1 kg of water, and 160 g of Mg(NO)6HO in 1 kg of water. The Ca(NO) Example Z-34 Solution is added to the Zn(CHO). Solution while shear 0418 ZnO:MgO:NiO (82.5:10:7.5); 500 g Batch ing, followed by the Mg(NO). The resulting 10 wt.% Solids precursor Solution is fed into a mixed flow Spray dryer 0419) 1.1 kg of Zn(CHO) is dissolved in 1.4 kg at a liquid feed rate to maintain inlet/outlet temperatures of de-ionized water, 12.5g of Ni(CHO) (Ni-acetate) in 1 kg 975/580 F., using a two-fluid nozzle with an air pressure of of water, and 315 g. Mg(NO) in 1 kg water. The Mg(NO) 65 psig. The residence time of the System is 10 Seconds as Solution is added to the Zn(CHO). Solution while shear defined above. The powder is collected using a cyclone. ing followed by the Ni(CHO) solution. The resulting 10 wt.% Solids precursor Solution is fed into a mixed flow Spray Example Z-29 dryer at a liquid feed rate to maintain inlet/outlet tempera tures of 975/580 F., using a two-fluid nozzle with an air 0408 ZnO:CaO:MgO (90:5:5) via Post-Processing pressure of 65 psig. The residence time of the system is 10 0409) 175 g of ZnO:CaO:MgO is put into aluminum Seconds as defined above. The powder is collected using a trays, which are then loaded into a convection oven. Under cyclone. US 2005/0230659 A1 Oct. 20, 2005 33 Example Z-35 0428 FIG. 15 illustrates a comparison of average pore diameter (nm) for pores less than 100 nm in diameter, BET 0420 ZnO:CuO (92.5:7.5); 500 g Batch Surface area (m/g) and pore volume (cm/g). It can be seen 0421) 1.2 kg of Zn(CHO) is dissolved in 2.6 kg that Z-37 and Z-39 have higher surface area, higher porosity de-ionized water and 110 g of Cu(NO) in 1 kg of water. and larger pore diameter than other Samples. The Cu(NO) solution is added to the Zn(CHO) solu tion while shearing. The resulting 10 wt.% solids precursor 0429 FIGS. 16(a) and 16(b) illustrate SEM photomicro Solution is fed into a mixed flow Spray dryer at a liquid feed graphs of Example Z-39. It is generally agreed that when rate to maintain inlet/outlet temperatures of 975/580 F., ZnO has a larger accessible Surface area HS removal will using a two-fluid nozzle with an air pressure of 65 psig. The be improved, thus, these two samples could have better HS residence time of the System is 10 Seconds as defined above. removal capability Such as higher Sulfur removal capacity The powder is collected using a cyclone. and lower Sulfur slip point (i.e., the point of absorbent failure Example Z-36 in the reactor bed). In addition, since the accessible Surface area is a function of not only the BET surface area but also 0422 ZnO:MgO:CuO (82.5:10:7.5); 500 g Batch to the average pore size, it is likely that these Samples have 0423 1.1 kg of Zn(CHO) is dissolved in 1.4 kg a more advantageous Structure as Sulfur absorbents. de-ionized water, 125 g of Cu(NO) in 1 kg of water, and 0430 Table 9 summarizes ZnO samples made by spray 315 g. Mg(NO) in 1 kg water. The Mg(NO) solution is added to the Zn(CHO). Solution while shearing followed drying Zn-nitrate and NH-nitrate as precursors followed by by the Cu(NO) solution. The resulting 10 wt.% solids the post processing at 300° C. Between them, Z-43 is made precursor Solution is fed into a mixed flow Spray dryer at a with 5 wt.% NH-nitrate while Z-3 is made with 20 wt.% liquid feed rate to maintain inlet/outlet temperatures of of NH-nitrate. Their corresponding post-processed 975/580 F., using a two-fluid nozzle with an air pressure of Samples, Z44 and Z4, have Similar particle size distributions 65 psig. The residence time of the System is 10 Seconds as (FIG. 14, dso-3 um) and BET surface area (6.1-6.7 m/g), defined above. The powder is collected using a cyclone. but the average pore size and pore Volumes are different, the 0424 Zn-Based Examples-Characterization former having much higher average pore size than the latter (FIG. 15). 0425 Table 7 summarizes various ZnO examples fabri cated by Spray drying Zn-nitrate precursors under different TABLE 9 processing conditions, as shown in Table 8. The details for Post the preparation of Examples Z-1 and Z-2 are given above. Inlet Temp. Processing Example Composition Precursor (°F) Conditions TABLE 7 Z-43 ZnO Zn-nitrate 975 N/A Inlet Temp Post-Processing (5% NH-nitrate) Example Composition Precursor (°F) Conditions Z-44 ZnO Z-43 300° C., 3 h. (5% NH-nitrate) Z-1 ZnO Zn-nitrate 975 N/A Z-3 ZnO Zn-nitrate 975 N/A Z-2 ZnO Z-1 300° C., 3 h. (20% NH-nitrate) Z-37 ZnO Zn-nitrate 975 N/A Z-4 ZnO Z-3 300° C., 3 h. Z-38 ZnO Z-37 300° C., 3 h. (20% NH-nitrate) Z-39 ZnO Zn-nitrate 975 N/A Z-40 ZnO Z-39 300° C., 3 h. Z-41 ZnO Zn-nitrate 975 N/A Z-42 ZnO Z-41 300° C., 3 h. 0431. The sample prepared with 20 wt.% NH-nitrate has Smaller average pore size (5.5 nm) and pore volume (0.008 cm/g) as compared to the sample fabricated from 5% 0426 NH-nitrate (14.9 nm vs 0.025 cm/g). TABLE 8 0432 FIGS. 17(a) and 17(b) illustrate SEM photomicro graphs for Example Z44. By Selectively controlling the type N Pressure Fan Speed Solid Weight Running and concentration of precursor additives, the pore properties Example (psig/CFM) (HZ?amp) (%) Time of ZnO can be selectively tailored. For HS removal, the Z-37 8O 60 5 38:50:OO Smaller pores (<5 nm) can be easily plugged during the early Z-39 8O 45 5 53:2O:OO Z-41 45 60 1O 34:OOOO stage of sulfurization of ZnO with HS, leaving the rest of Z-2 65/5.9 60/3.OO 1O 2 ZnO internal Surface inaccessible to HS and resulting in low absorption capacity. 0427 FIG. 14 illustrates the particle size distribution 0433 Table 10 Summarizes ZnO samples fabricated by (PSD) for the Examples listed in Table 6. The PSDs are Spray drying with NH-Oxalate and NH-carbonate as pre Similar and the average particle size (do) for the spray dried cursors, followed by post processing at different tempera Samples is around 3 m and the do for the post-processed tures. After post-processing at 300° C., the sample from the Samples is around 6 um. oxalate precursor is only partially converted to ZnO. US 2005/0230659 A1 Oct. 20, 2005 34 TABLE 10 Inlet Post Temp. Processing Example Composition Precursor (F) Conditions Z-5 ZnO/partial ZnCO, Zn(NO)/NH(CO) 975 N/A Z-6 ZnCO/little ZnO Z-6 300° C., 3 h. Z-12 ZnCO/little ZnO Zn(OAc)/NH4)2CO 975 N/A Z-13 ZnO/partial ZnCO Z-12 300° C., 3 h. Z-14 ZnO Z-12 500° C., 3 h. Z-7 ZnO Zn(NO)/NH(CO) 975 N/A (Partial conv. carbonate) Z-8 ZnO Z-7 300° C., 3 h. (Partial conv. carbonate) 0434 However, post-processing the oxalate at 500 C. can completely convert the powder into ZnO. From the PSD TABLE 12-continued shown in FIG. 14, it can be seen that the partially converted ZnO has a larger particle size (ds of about 5 to 7 um) than Inlet Post pure ZnO made by Spray drying. The lower post processing Temp. Processing treatment preserves the Sample porosity to a higher eXtent Example Composition Precursor (F) Conditions up to 20 nm average pore size for Example Z-6. FIGS. 18(a) Z-16 ZnO Z-15 300° C., 3 hr and 18(b) illustrate SEM photomicrographs of Example Z-6. (15% Al-O.) Z-17 ZnO Zn-nitratef 975 N/A 0435 Table 11 Summarizes ZnO samples made by spray (15% Al2O3) Al2O3 drying precursors including Zn-acetate and lactic acid, Z-18 ZnO Z-17 300° C., 3 hr including post-processing at 300° C. and 500 C. The (15% Al-O.) powder maintains a similar PSD (ds of about 6 um), even Z-48 ZnO Zn(NO)/o- 975 N/A after it is post processed at 500 C. However, the porosity is (15% Al2O3) Al2O3 quite different, as shown in FIG. 15. Post-processing at Z-49 ZnO Z-48 300° C., 3 hr relatively low temperatures (300° C.) preserves the higher (15% Al-O.) Surface area, pore Volume and average pore diameter. Z-19 ZnO Zn(OAc)/Al2O3 975 N/A (15% Al-O.) TABLE 11 Z-2O ZnO Zn(OAc)/Al2O3/ 975 N/A (15% Al-O.) NHNO, Inlet Temp. Post-Processing Z-SO ZnO Zn-nitratef 975 N/A Example Composition Precursor (°F) Conditions (25% Al-O.) Al-O. Z-51 ZnO Z-SO 300° C., 3 hr Z-9 ZnO Zn(OAc)/ 975 N/A lactic acid (25% Al-O.) Z-10 ZnO Z-9 300° C., 3 h. Z-11 ZnO Z-9 500° C., 3 h. 0438. The addition of alumina into Example Z45 and Z-15 is by the use of Al-nitrate in the precursor solution, 0436) Al-O/ZnO Samples while the alumina in Examples Z-17, Z-49, Z-23 and Z-50 0437 Table 12 Summarizes ZnO samples with different is formed from an alumina dispersion. AlOs content and utilizing Al-Os from different sources and the Samples obtained by post-processing at different tem 0439. The characterization data shown in FIG. 19 (par peratures. Details of the synthesis of Examples Z-15, Z-16, ticle size distribution), FIG.20 (BET and pore volume) and Z-17, Z-18, Z-19 and Z-20 are given above. FIG. 21 (average pore diameter) illustrates that the major difference between the examples is the average pore diam TABLE 12 eter. The example made from Al-nitrate has higher BET Inlet Post Surface area, but the average pore diameter is less than 5 nm, Temp. Processing which is much Smaller than the Example fabricated using Example Composition Precursor (F) Conditions particulate Al-O. The Smaller average pore diameter can be Z-45 ZnO Zn(OAC)f 975 N/A more easily plugged during the early Stage of H2S removal, (5% Al-O.) AlNO. leaving the rest of Surface inaccessible to HS. Z-46 ZnO Z-45 300° C., 3 hr (5% Al-O.) Z-47 ZnO Z-45 300° C., 3 hr 0440 SiO/ZnO and ZnO Containing Al-O and SiO, (5% Al-O.) Z-15 ZnO Zn-nitratef 975 N/A 0441) Table 13 summarizes ZnO samples containing SiO, (15% Al-O.) Al(NO) and Al-O and their post processing conditions. Typical fabrication parameters are given above for Example Z-22. US 2005/0230659 A1 Oct. 20, 2005 35 raising the temperature to 750° C. or 800° C. The weight loss TABLE 13 of the absorbent is then recorded as a function of time until a stable weight is reached and the Sample is then cooled Inlet Post down to room temperature. All carbonation takes place at Temp. Processing 600 C., and the sample pre-treatment and decarbonation Example Composition Precursor (F) Conditions temperature are kept the same. Z-21 ZnO (5% SiO.) Zn(NO).SiO, 975 N/A Z-22 ZnO (5% SiO.) Z-21 3OO C.3 h. 0448 Referring to FIG. 25, the initial absorption capac Z-52 ZnO (15% SiO.) Zn(NO).SiO, 975 N/A Z-53 ZnO (15% SiO) Z-52 300° C., 3 h. ity of the commercial CaO is about 22 g CO2/100 g of Z-23 ZnO Zn-nitratef 975 N/A Sample and the peak absorption capacity is about 35 g (10%. Al-O.s, Al2O3/SiO2 CO/100 g of sample (Cycle 5). It is noteworthy that the 5%. SiO.) absorption capacity fluctuates from about 15 g to 35 g Z-24 ZnO Z-23 300° C., 3 h. CO2/100g of Sample. Such fluctuations in absorption capac (10%. Al-O.s, ity are undesirable for commercial operations since the 5%. SiO.) device must then be designed to accommodate the lowest capacity (e.g., to accommodate 15 g CO2/100 g for the 0442 FIGS. 22 and 23 compare the PSD (FIG.22) and sample illustrated in FIG. 25). the pore Volume, BET Surface area and average pore diam 0449 FIGS. 26 and 27 illustrate the change in particle eter (FIG. 23). The samples have similar physicochemical size distribution (do, do and doo), pore Volume (for pores properties. <100 nanometers), BET surface area and pore diameter for 0443 Cycling of Absorbents the commercial CaO powder after 27 cycles. It is evident that Sintering of the powder has occurred, resulting in a 0444 FIG. 24 illustrates the carbonation and decarbon Significant increase in average particle size (FIG. 26). The ation kinetics of CO using commercially available CaO pore Volume and average pore diameter decreased slightly (J.T. Baker) as measured by thermogravimetric analysis and the BET surface area increased slightly (FIG. 27). (TGA). FIG. 24 illustrates that the carbonation of CaO is divided into two distinct regions, the fast region and the slow 0450 Table 14 Summarizes the change in BET surface region. The fast region (less than 800 Seconds) corresponds area, pore Volume and pore diameter after cycling Select to the easily accessible CaO active siteS present on the absorbent materials according to the present invention 12 external surface and the slow region (1000 to 10,000 sec times. onds) corresponds to the penetration of CO through the carbonate layer into unreacted CaO near the particle core. TABLE 1.4 The portion of CaO reactivity and kinetics in these two regions depend on the material properties and operating As-Made After 12 Cycles conditions. Decarbonation takes place (>10,000 seconds) Average Average when the bed temperature is raised up to 750° C. or higher. Pore Pore Pore Pore FIG. 24 illustrates that the overall absorption capacity, BET Volume Diameter BET Volume Diameter expressed as a CaO reaction fraction is around 40 mol.% at Example (m/g) (cm/g) (nm) (m/g) (cm/g) (nm) a time of 10000 seconds. As used herein, the CaO reaction A-7 60.1 O.242 16.1 12.37 OO612 19.5 fraction is the ratio of CaO converted to CaCO relative to A-18 61.7 O.235 15.2 7.97 O.O44 22.2 A-22 17.5 0.055 14 6.07 O.O19 12.7 the amount of available absorbent compound (e.g., CaO) in A-20 15.7 O.O66 15.1 2.7 O.O12 17.5 the absorbent material, usually expressed as a mol. 76. A-4 17.7 O.O19 9.7 5.48 O.O12 8.9 A-12 7.7 O.O58 13.1 O.66 OOO1 8.5 0445 Based on this interpretation, for the standard A-16 5.6 0.057 13.2 1.65 O.O.33 8.11 sample measurements illustrated in FIG. 24, about 50% of the total absorption capacity is consumed by the available surface area of the absorbent, and the remaining 50% of the 0451 FIG. 28 illustrates the absorption capacity in terms capacity requires a long reaction time. It is therefore advan of CaO reaction fraction through multiple cycles for com tageous to increase the absorbent available Surface area to mercial CaO (3 samples) and CaO obtained from different enable faster absorption. This is illustrated in more detail Spray processing methods, namely Spray pyrolysis below. (Examples A-14 and A-15), and conversion in a spray dryer 0446 FIG. 25 illustrates the absorption performance of with post-processing (Examples A-12 and A-13). the commercial CaO sample over 26 cycles with the car 0452 Referring to FIG. 28, the capacity of some CaO bonation occurring at 600 C. and decarbonation occurring absorbents made by Spray pyrolysis is only slightly higher at 750° C. compared to the commercial CaO absorbents (30 mol.% vs. 0447 For this example and the remaining examples 25 mol. 9% CaO reaction fraction in the first cycle). It can herein, a cycle of absorbent-containing material includes also be seen that CaO Samples from oxalate precursors heating the Sample disposed in a crucible in a thermogravi (Example A-12, by XRD CaCO and Example A-13, by metric analysis (TGA) unit to 750° C. or 800° C. at a rate of XRD a mix of CaCOs an CaO, made by spray drying 10-20°C/min in the presence of N until/the TGA baseline followed by post-processing at 500 C. and 750° C., respec is stable. The crucibles are then cooled down to 7401t/he tively) have a high initial absorption capacity-up to 80 mol. carbonation temperature (600° C.), and pure CO is intro % CaO reaction fraction, nearly three times higher than duced into the //chamber. Once the stable baseline is commercial CaO. These results clearly demonstrate the reached, decarbonation Starts by Switching the gas to N2 and advantages of Spray processing in the development of CaO US 2005/0230659 A1 Oct. 20, 2005 36 based absorbents. However, the absorption capacity 0459 MgO can also be added to the absorbent materials decreases very rapidly after a limited number of cycles in accordance with the present invention. FIG. 37 illustrates (from 85 mol. 9% to 32 mol. 96) due to the loss of micro the performance achieved by adding MgO into CaO at Structure and porosity, as mentioned above. Therefore, fur different ratios of CaO:MgO and also by adding Al-O. It ther addition of materials into CaO is necessary to prevent can be seen that CaO:MgO with different ratios (from 90:10 the materials from Sintering during temperature Swing to 50:50) made by spray drying followed by post processing operation and to maintain the cyclability. at 500 C. have a similar initial absorption capacity in terms of CaO reaction fraction. However, the stability is quite 0453 FIG.29 illustrates a comparison between the initial different-only a CaO:MgO ratio of 50:50 stabilizes the carbonation and decarbonation profiles of CaO absorbent recyclability. Example A-7 with a CaO:MgO ratio of 50:50 materials from different Sources including a commercial retains a capacity of over 90% even after 12 cycles, while the samples. The CaO fabricated from calcium nitrate and capacity of Example A-20 with a CaO:MgO ratio of 90:10 ammonium oxalate precursors and post processed at 500 C. decreases to less than 60% after 12 cycles. The initial (A-12) or at 750° C. (A-13) has faster kinetics and higher differences of carbonation/decarbonation kinetics among reactivity in the fast region and improved kinetics upon Samples with the same composition depend on the Specific decarbonation. conditions used for Spray processing, as is illustrated in FIG. 0454 FIGS. 30 and 31 illustrate the particle size distri 38. However, both Example A-26 made by spray pyrolysis bution (FIG. 30) and the pore volume, average pore diam and Example A-7 made by Spray drying followed by post eter (pores <100 nanometers) and BET surface area (FIG. processing at 500 C. have similar carbonation/decarbon 31) for Examples A-4, A-12, A-5 and A-13. It is evident that ation rates. This observation Supports the conclusion that the addition of 10%. Al-O reduces the initial particle size of absorbents with good absorption kinetics and recyclability the absorbent materials (Example A-4 compared to Example can be derived by various spray processing methods, as A-12 and Example A-5 compared to Example A-13) and described in detail above, as long as the right combination increases the average pore Volume and Surface area of the of composition and processing conditions have been uti powders. lized. 0455 FIG. 32 illustrates the CaO absorption capacity in 0460. As shown above, absorbents with various compo terms of CaO reaction fraction as a function of the number sitions deliver high reactivity for CO absorption in terms of of cycles for 3 different examples. The addition of 10 wt.% mol. 9% fraction of CaO. The composition of the inert Al-O to CaO in Examples A-4 and A-5 can significantly additives is-not limited to Al-O and MgO-other oxides improve the absorbent Stability while maintaining the origi such as TiO, or a combination thereof can be added to the nal high CO2 absorption, retaining an absorption capacity absorbent formulation to produce an absorbent with faster above 70 mol.% for each cycle up to 12 cycles. One reason kinetics, as is illustrated in FIG. 39. The Example illustrated for good cyclability of 10 wt.% Al-O/CaO samples is the in FIG. 39 is a composite of CaO and TiO (CaO:TiO=4:1) particle Size Stability after the multiple cycles, as demon fabricated by spray drying and post-processing at 500 C. for strated in Table 15. 3 hours. 0461 From a practical point of view, the total absorption TABLE 1.5 capacity in terms of CO weight or weight percentage based Particle Size (um) on the total weight of the absorbent is more important. By din dens don comparing the effects of inert additives Such as Al-O and MgO, both showing high initial capacity and Stable recy Example Composition Before Cycling After Cycling clability at the proper composition and Spray processing A-12 100% CaO 2.0, 5.1, 13.2 5.6, 14.5, 26.2 conditions, significantly improved results are achieved with A-4 90% CaO 1.7, 4.4, 11.7 1.0, 2.7, 11.4 respect to the total CO capacity per gram absorbent by 10%. Al-O. A-28 57% CaO 1.2, 5.9, 17.1 3.2, 7.5, 22.4 using only a Small portion of 10 wt.% Al-O into CaO, as 43% Al-O. compared to CaO:MgO with 50 wt.% MgO. For example, FIG. 40 illustrates the absorption capacity for Examples A-22 and A-7 expressed as the total CO2 capacity based on 0456. It is noteworthy that the PSD for Example A4 the mass of total absorbent. Each example has a relatively actually decreases after cycling. constant absorption capacity through 12 cycles and each is close to the theoretical value (66.78 gCO2/100 g absorbent 0457 FIGS. 33(a) and (b) illustrate the SEM photomi crographs of a commercially available CaO powder before for A-22 and 39.28 gCO2/100 g absorbent for A-7). and after 27 cycles. FIGS. 34(a) and (b) illustrate SEM 0462 FIG. 41 illustrates the carbonation and decarbon photomicrographs of Example A-12 before and after 12 ation kinetics for four examples according to the present cycles. FIGS. 35(a) and (b) illustrate SEM photomicro invention. It can be seen that the larger percentage of MgO graphs of Example A-4 before and after 12 cycles. in the CaO Sample, the faster kinetics in the first carbonation region. Also the addition of Al-O can improve the kinetics 0458 FIG. 36 illustrates the change in particle size in first carbonation region, as Seen by comparing Examples distribution for Al-O/CaO examples according to the present invention before and after 12 cycles. It is evident that A-20 and A-22. The most rapid decarbonation kinetics occur the examples having good recyclability (Examples A-4 and with Example A-18. A-5) also exhibit an overall decrease in particle size. 0463 FIG. 42 illustrates the particle size distribution Example A-28 (43% Al2O) shows an increase in the do and before and after 12 cycles for certain CaO:MgO examples, doo size ranges. with and without Al-O additions. FIG. 43 illustrates the US 2005/0230659 A1 Oct. 20, 2005 37 pore Volume, BET Surface area and average pore diameter (pores-100 nanometers) for the same examples. The pres TABLE 1.7 ence of MgO effectively increases the porosity, particularly at high MgO contents, and maintains a Small particle size. Sample Composition Extrudate A-14 CaO EA-14 0464) Pelletization A-15 CaO EA-15 A-23 CaO:MgO (50:50 at. 96) EA-23 0465. The following illustrates CO absorbent perfor A-24 CaO:MgO (50:50 at. 96) EA-24 mance after pelletizing and how the Selected powder pre A-25 CaO:MgO (50:50 at. 96) EA-25 cursors for pellet extrusion affect CO absorption by altering A-26 CaO:MgO (50:50 at. 96) EA-26 the microstructure and porosity. 0466 Table 16 Summarizes examples of extruded pellets 0471. The details of the powder preparation conditions made from powders that were produced on a Spray dryer are listed in Tables 4 and 5. without further post-processing (see Tables 4 and 5 for the Synthesis conditions). Among the extrudates, the binder 0472. The amount of the binders used for extrusion for (boehmite alumina) used for extrusion is kept the same. these powders are all kept the Same. 0473 FIGS. 49 and 50 show the results of CO carbon TABLE 16 ation reactivity and cyclability over the extrudates. FIG. 49 Example Powder Composition Extrudate illustrates the CaO reaction fraction over multiple cycles. For the Examples illustrated in FIGS. 49 to 61, carbonation A-2 Ca-Oxalate EA-2 occurs at 600 C. and decarbonation occurs at 800 C. At the A-3 Ca-Oxalate EA-3 5% Al-O. initial Stage, the CaO reactivity is higher, then gradually A-3A Ca-Oxalate EA-3A becomes stable and levels at around 60 mol. % during 25% Al-O multiple cycles. AS compared to the extrudates from A-6 CaO:MgO (50:50 wt.%) EA-6 A-7 CaO:MgO (50:50 wt.%) EA-7 CaO:MgO, the extrudates from CaO (EA-14 and EA-15) 5% Al-O have a low Stability and the absorption capacity gradually A-19 CaO:MgO (90:10 wt.%) EA-19 decreases during multiple cycles. A-21 CaO:MgO (90:10 wt.%) EA-21 5% Al-O. 0474 FIG. 50 illustrates the total CO capacity over the same cycle test as illustrated in FIG. 49. The capacity for the extrudates made from CaO powders (EA-14 and EA-15) is 0467 FIGS. 44 and 45 illustrate the carbonation perfor higher than the extrudates made from CaO:MgO powders mance of extrudates formed from precursors including cal (EA-23, EA-24, EA-25 and EA-26). However, the extru cium oxalate or calcium carbonate. FIG. 44 illustrates the dates from CaO:MgO powders show more stable recycla CaO reaction fraction and FIG. 45 illustrates the total CO bility and the capacity for CO2 removal is around 22g CO capacity in mass CO2 per mass of absorbent. After pelleti per 100 g absorbent. zation, CaO reactivity to CO carbonation decreases due to microStructural changes caused by the presence of a binder. 0475 FIGS. 51 and 52 illustrate the cyclability of Extru In the case of sample EA-3A the activity to CO carbonation date EA-26 over 100 cycles. FIG. 51 illustrates the CaO reaction fraction and FIG. 52 illustrates the total CO is very low due to the use of large amount of Al-O in the capacity. (The deviations at Cycles 40 and 72 are due to powder precursor Sample, Similar to the results described for depletion of the CO2 Source during testing). This extrudate the non-pelletized powder. The presence of a large amount maintains a high absorption capacity over at least 100 of Al-O will possibly cause it to react with CaO to form a cycles. new phase Such as a spinel Structure and prevent access of CO to unreacted CaO. 0476 Pellets can also be formed from powders made by Spray drying and post-processing according to the present 0468 FIG. 46 illustrates a comparison of the carbonation invention. Table 18 lists several such examples. and decarbonation kinetics for Selected extrudates. 0469 FIG. 47 illustrates the absorption capacity over 116 TABLE 1.8 cycles of Extrudate EA-21, which is pelletized from a Extrudate Powder Composition Process Conditions powder made by Spray drying with a composition of Ca EA-101 CaO:MgO (50:50 by wt.) SD, PP at 500° C. oxalate and Mg-Oxalate precursor containing 5 wt.%. Al2O. EA-102 CaO:MgO (50:50 by wt.) SD, PP at 750° C. It can be seen that CaO reactivity to CO carbonation is EA-103 CaO:MgO (50:50 by wt.) SD, PP at 500° C. around 40 mol.% and is very stable over the 116 cycles of EA-104 95% CaO SD, PP at 750° C. 5% CaTiO, the test. (The dips in absorption at cycle numbers 60 and 108 EA-105 CaO:MgO (50:50)/CaTiO, SD, PP at 650° C. are due to the depletion of the CO Source during testing). (3/1 by at.) The absolute capacity for CO2 absorption, illustrated in FIG. EA-106 CaO/CatiC) SD, PP at 750° C. (3/1 by at.) 48, during the same cycling test is around 23 to 25 grams EA-107 Ca-Oxalate SD, PP at 500° C. CO/per 100 grams of extrudate. 5 wt.% Al-O. EA-108 Ca-Oxalate SD, PP at 750° C. 0470 Table 17 lists the powders made from spray pyroly sis used for additional pelletization testing. US 2005/0230659 A1 Oct. 20, 2005 38 (b) atomizing said precursor Solution to form precursor TABLE 18-continued droplets comprising Said first precursor, Extrudate Powder Composition Process Conditions (c) heating said precursor droplets remove liquid there from and form dried precursor droplets, and EA-109 CaO:MgO (80:20 by wt.) SD, PP at 500° C. EA-110 CaO:MgO (80:20 by wt.) SD, PP at 500° C. (d) converting said dried precursor droplets to a particu late absorbent material. 2. An absorbent material as recited in claim 1, wherein 0477 FIGS. 53 and 54 illustrate the reactivity and cycla Said heating Step and Said converting Step occur Sequentially bility of extrudate EA-101 made from the powder with CaO/MgO (50:50 wt. ratio) followed by post processing at in a spray pyrolysis. 500 C. FIG. 53 illustrates the CaO reaction fraction over 66 3. An absorbent material as recited in claim 1, wherein cycles and FIG. 54 illustrates the CO capacity for the same Said heating Step forms an intermediate compound capable cycle tests. The dips in CaO reaction fraction (e.g., at Cycle of being post-processed to form a particulate absorbent 42) is believed to be due to a depletion of the CO, source. material, and wherein Said converting Step comprises heat These figures demonstrate that the absorbent powder formed ing Said intermediate compound to form Said particulate by Spray drying and post-processing at 500 C. can be absorbent material. formed into a pellet having a high absorption capacity over 4. A particulate absorbent material as recited in claim 1, a large number of cycles. wherein Said first precursor is Selected from the group consisting of a metal nitrate, a metal acetate, a metal oxalate 0478 FIGS. 55 and 56 illustrate the reactivity and cycla and a metal hydroxide. bility of extrudate EA-102 made from the powder with CaO:MgO (50:50 wt. ratio) followed by post processing at 5. A particulate absorbent material as recited in claim 1, 750° C. FIG.55 illustrates the CaO reaction fraction over 66 wherein Said first precursor comprises a metal oxalate. cycles and FIG. 56 illustrates the CO capacity for the same 6. A particulate absorbent material as recited in claim 1, cycle tests. These examples were tested at the same time as wherein Said absorbent material comprises a metal oxide. the examples illustrated in FIGS. 53 and 54, and the dips in 7. A particulate absorbent material as recited in claim 1, CaO reaction fraction (e.g., at Cycle 42) is believed to be due wherein Said absorbent material comprises a metal oxide to a depletion of the CO Source. These figures demonstrate Selected from Group 1 and Group 2 metal oxides. that the absorbent powder formed by spray drying and 8. A particulate absorbent material as recited in claim 1, post-processing at 750° C. can be formed into a pellet having wherein Said absorbent material comprises a metal oxide a high absorption capacity over a large number of cycles. Selected from the group consisting of magnesium oxide, 0479 FIGS. 57 and 58 illustrate the reactivity and cycla calcium oxide, Strontium oxide and barium oxide. bility of extrudate EA-105 made from the powder with 9. A particulate absorbent material as recited in claim 1, CaO:MgO (50:50 wt. ratio) containing 33 mol.% of CaTiO, wherein Said absorbent material comprises calcium oxide. followed by post processing at 750° C. FIG. 57 illustrates 10. A particulate absorbent material as recited in claim 1, the CaO reaction fraction over 66 cycles and FIG. 58 wherein Said absorbent material comprises a metal oxide and illustrates the CO2 capacity for the Same cycle tests. Again, wherein Said precursor Solution comprises a metal Salt the dips in capacity (e.g., at cycles 17, 30 and 38) are due to Selected from the group consisting of a metal oxalate Salt and depletion of the CO2 Source. a metal hydroxide Salt. 11. A particulate absorbent material as recited in claim 1, 0480 FIGS. 59 and 60 illustrate the cyclability of extru wherein Said absorbent material comprises a misch metal. date EA-108 made from the powder with 10 wt.% Al-O 12. A particulate absorbent material as recited in claim 1, followed by post processing at 750° C. FIG. 59 illustrates wherein Said heating Step comprises heating Said droplets in the CaO reaction fraction over 64 cycles and FIG. 60 the presence of an OXygen-containing gas. illustrates the CO2 capacity for the same cycle tests. 13. A particulate absorbent material as recited in claim 1, 0481 FIG. 61 illustrates the CaO reaction fraction for wherein Said precursor Solution further comprises a mor Extrudate EA-107 made from the powder with 10 wt.% phology-enhancing agent. AlO, followed by post processing at 500° C. over 64 cycles. 14. A particulate absorbent material as recited in claim 1, 0482 While various embodiments of the present inven wherein Said precursor Solution further comprises a mor tion have been described in detail, it is apparent that modi phology-enhancing agent Selected from the group consisting fications and adaptations of those embodiments will occur to of lactic acid, glycine, alcohols, ammonium nitrate, poly those skilled in the art. However, it is to be expressly merS and carbohydrazide. understood that Such modifications and adaptations are 15. A particulate absorbent material as recited in claim 1, within the Spirit and Scope of the present invention. wherein Said precursor Solution further comprises a precur Sor to a compound Selected from the group consisting of aluminum oxide, magnesium oxide, Silicon oxide and tita What is claimed is: nium oxide. 1. A particulate absorbent material for the absorption of a 16. A particulate absorbent material as recited in claim 1, chemical Species from a fluid, wherein Said absorbent mate wherein Said particulate absorbent material comprises rial is fabricated by a proceSS comprising the Steps of: CaO:MgO. 17. A particulate absorbent material as recited in claim 1, (a) providing a precursor Solution comprising at least a wherein Said precursor Solution further comprises a precur first precursor to an absorbent compound; Sor to magnesium oxide. US 2005/0230659 A1 Oct. 20, 2005 39 18. A particulate absorbent material as recited in claim 1, 38. A particulate absorbent material as recited in claim 1, wherein Said precursor Solution further comprises magne wherein Said absorbent material comprises an absorbent sium nitrate. compound having an absorption capacity of at least about 90 19. A particulate absorbent material as recited in claim 1, mol. 76. wherein Said precursor Solution further comprises a precur 39. Aparticulate absorbent material as recited in claim 37, Sor to alumina. wherein Said absorbent compound maintains Said absorption 20. A particulate absorbent material as recited in claim 1, capacity over at least 100 cycles. wherein Said precursor Solution further comprises particu 40. A particulate absorbent material as recited in claim 1, late alumina. wherein Said heating Step comprises heating Said droplets in 21. A particulate absorbent material as recited in claim 1, a spray dryer. wherein Said precursor Solution further comprises a precur 41. A particulate absorbent material adapted for the Sor to a metal Selected from the group consisting of Mg, Ni, absorption of a chemical Species from a fluid, wherein Said Zn and Cu. particulate absorbent material comprises an intimate mixture 22. A particulate absorbent material as recited in claim 1, of at least a first absorbent compound and a metal oxide that wherein Said heating Step comprises heating Said precursor is different than Said first absorbent compound, and wherein droplets to a temperature of at least about 300° C. Said particulate absorbent material has a Surface area of at 23. A particulate absorbent material as recited in claim 1, least about 5 m/g. wherein Said atomizing Step comprises atomizing Said pre 42. A particulate absorbent material as recited in claim 41, cursor Solution using a spray nozzle. wherein Said absorbent compound is Selected from Group 1 24. A particulate absorbent material as recited in claim 1, and Group 2 metal oxides. wherein Said atomizing Step comprises atomizing Said pre 43. Aparticulate absorbent material as recited in claim 41, cursor using ultrasonic transducers. wherein Said absorbent compound is a calcium compound. 25. A particulate absorbent material as recited in claim 1, 44. Aparticulate absorbent material as recited in claim 41, wherein Said particulate absorbent material has an average wherein Said metal oxide is Selected from the group con size of from about 1 um to about 50 lum. Sisting of Al-O, MgO, SiO2 and TiO2. 26. A particulate absorbent material as recited in claim 1, 45. Aparticulate absorbent material as recited in claim 41, further comprising the Step of pelletizing Said particulate wherein Said particulate absorbent material is in the form of absorbent material. Substantially spherical particles. 27. A particulate absorbent material as recited in claim 1, further comprising the Step of coating Said particulate absor 46. Aparticulate absorbent material as recited in claim 41, bent material on a Support Structure. wherein said Surface area is at least about 10 m/g. 28. A particulate absorbent material as recited in claim 1, 47. Aparticulate absorbent material as recited in claim 41, wherein Said particulate absorbent material has a Substan wherein said Surface area is at least about 15 m/g. tially Spherical morphology. 48. Aparticulate absorbent material as recited in claim 41, 29. A particulate absorbent material as recited in claim 1, wherein said Surface area is at least about 30 m/g. further comprising the Step of heating Said particulate absor 49. Aparticulate absorbent material as recited in claim 41, bent material. wherein Said particulate absorbent material has a pore Vol 30. A particulate absorbent material as recited in claim 1, ume of at least about 0.01 cm/g. wherein Said particulate absorbent material has a pore Vol 50. Aparticulate absorbent material as recited in claim 41, ume of at least about 0.04 g/cm. wherein Said particulate absorbent material has a pore Vol 31. A particulate absorbent material as recited in claim 1, ume of at least about 0.04 cm/g. wherein Said particulate absorbent material has a pore Vol 51. Aparticulate absorbent material as recited in claim 41, ume of at least about 0.15 g/cm. wherein Said particulate absorbent material has a pore Vol 32. A particulate absorbent material as recited in claim 1, ume of at least about 0.15 cm/g. wherein Said particulate absorbent material has a Surface 52. A particulate absorbent material as recited in claim 41, area of at least about 15 m/g. wherein said metal oxide comprises from about 1 wt.% to 33. A particulate absorbent material as recited in claim 1, 50 wt.% of said particulate absorbent material. wherein Said particulate absorbent material has a Surface 53. Aparticulate absorbent material as recited in claim 41, area of at least about 30 m/g. where said metal oxide comprises from about 5 wt.% to 34. A particulate absorbent material as recited in claim 1, about 25 wt.% of said particulate absorbent material. wherein said absorbent material is adapted to absorb CO 54. Aparticulate absorbent material as recited in claim 41, and has an absorption capacity of at least about 20 grams wherein Said particulate absorbent compound has an absorp CO, per 100 grams of unreacted absorbent material. tion capacity of at least about 50 mol. 76 for at least one 35. Aparticulate absorbent material as recited in claim 34, Selected chemical Species. wherein Said absorbent compound maintains Said absorption 55. Aparticulate absorbent material as recited in claim 41, capacity over at least 100 cycles. wherein Said particulate absorbent compound has an absorp 36. A particulate absorbent material as recited in claim 1, tion capacity of at least about 70 mol. 76 for at least one wherein said absorbent material is adapted to absorb CO Selected chemical Species. and has an absorption capacity of at least about 30 grams 56. Aparticulate absorbent material as recited in claim 41, CO, per 100 grams of unreacted absorbent material. wherein Said particulate absorbent compound has an absorp 37. A particulate absorbent material as recited in claim 1, tion capacity of at least about 90 mol. 76 for at least one wherein Said absorbent material comprises an absorbent Selected chemical Species. compound having an absorption capacity of at least about 70 57. Aparticulate absorbent material as recited in claim 41, mol. 76. wherein Said absorbent compound has an absorption capac US 2005/0230659 A1 Oct. 20, 2005 40 ity of at least about 50 mol. 9% for at least one selected 74. A method as recited claim 61, wherein Said precursor chemical Species after at least 100 cycles. Solution further comprises a Second precursor, Said Second 58. A particulate absorbent material as recited in claim 41, precursor being Selected to form alumina. wherein Said absorbent compound has an absorption capac 75. A method as recited claim 61, wherein said precursor ity of at least about 70 mol. 9% for at least one selected Solution further comprises a Second precursor comprising chemical Species after at least 100 cycles. particulate alumina. 59. A particulate absorbent material as recited in claim 41, 76. A method as recited claim 61, wherein said precursor wherein Said absorbent compound has an absorption capac Solution further comprises a Second precursor, Said Second ity of at least about 90 mol. 9% for at least one selected precursor being Selected to form a metal Selected from the chemical Species after at least 100 cycles. group consisting of Mg, Ni, Zn and Cu. 60. Aparticulate absorbent material as recited in claim 41, 77. A method as recited claim 61, wherein said heating wherein Said particulate absorbent material is pelletized. Step comprises heating Said precursor droplets to a tempera 61. A method for the fabrication of a particulate absorbent ture of at least about 300° C. material, comprising the Steps of: 78. A method as recited in claim 61, wherein said con (a) atomizing a liquid-containing precursor Solution to Verting Step comprised heating Said intermediate compound. form precursor droplets, Said precursor Solution com 79. A method as recited claim 61, wherein said atomizing prising at least a first precursor to an absorbent com Step comprises atomizing Said precursor Solution using a pound; Spray nozzle. 80. A method as recited claim 61, wherein said atomizing (b) heating said precursor droplets to form dried precursor Step comprises atomizing Said precursor Solution using droplets, and ultraSonic transducers. (c) converting said dried precursor droplets to an absor 81. A method as recited claim 61, wherein said particles bent material comprising an absorbent compound. have an average size of from about 1 um to about 50 lim. 62. An absorbent material as recited in claim 61, wherein 82. A method as recited claim 61, further comprising the Said heating Step and Said converting Step occur Sequentially Step of pelletizing Said particulate absorbent material. in a spray pyrolysis. 83. A method as recited claim 61, further comprising the 63. An absorbent material as recited in claim 61, wherein Step of coating Said particulate absorbent material on a Said heating Step forms an intermediate compound capable Support Structure. of being post-processed to form a particulate absorbent 84. A method as recited claim 61, wherein Said particu material, and wherein Said converting Step comprises heat lates have Substantially spherical morphology. ing Said intermediate compound to form Said particulate 85. A method as recited in claim 61, wherein said absor absorbent material. bent material comprises CaO. 64. A method as recited in claim 61, wherein said first 86. A method as recited claim 61, wherein said absorbent precursor is at least partially Soluble in Said precursor material comprises ZnO. Solution. 87. A method as recited claim 61, wherein said absorbent 65. A method as recited in claim 61, wherein said first material comprises MnO:ZrO. precursor is Selected from the group consisting of metal 88. A method as recited claim 61, wherein said absorbent oxalates and metal hydroxides. material comprises CeO2:ZrO2. 66. A method as recited claim 61, wherein said first 89. A method as recited claim 61, wherein said absorbent precursor is Selected from the group consisting of calcium material comprises a metal hydride. nitrate, calcium acetate, calcium oxalate and calcium 90. A method for the fabrication of a particulate NO hydroxide. absorbent material, comprising the Steps of: 67. A method as recited claim 61, wherein said first (a) providing a precursor Solution comprising at least a precursor comprises calcium oxalate. first precursor to a NO absorbent compound; 68. A method as recited claim 61, wherein said heating Step comprises heating Said droplets in the presence of an (b) atomizing said precursor Solution to form precursor OXygen-containing gas. droplets; 69. A method as recited claim 61, wherein said precursor (c) heating Said precursor droplets to form dried precursor Solution further comprises a morphology-enhancing agent. droplets; 70. A method as recited claim 61, wherein said precursor Solution further comprises a morphology-enhancing agent and Selected from the group consisting of lactic acid, glycine, (d) converting said dried precursor droplets to an absor alcohols, ammonium nitrate, polymers and carbohydrazide. bent material comprising an absorbent compound. 71. A method as recited claim 61, wherein Said precursor 91. An absorbent material as recited in claim 90, wherein Solution further comprises a Second precursor, Said Second Said heating Step and Said converting Step occur Sequentially precursor being Selected to form a compound Selected from in a spray pyrolysis. the group consisting of aluminum oxides, magnesium 92. An absorbent material as recited in claim 90, wherein oxides, Silicon oxides and titanium oxides. Said heating Step forms an intermediate compound capable 72. A method as recited claim 61, wherein Said precursor of being post-processed to form a particulate absorbent Solution further comprises a Second precursor, Said Second material, and wherein Said converting Step comprises heat precursor being Selected to form magnesium oxide. ing Said intermediate compound to form Said particulate 73. A method as recited claim 61, wherein said precursor absorbent material. Solution further comprises a Second precursor comprising 93. A method as recited claim 90, wherein said NO) magnesium nitrate. absorbent compound comprises a compound Selected from US 2005/0230659 A1 Oct. 20, 2005 the group consisting of the oxides, hydroxides or carbonates 103. A method for the fabrication of a reversible hydrogen of the alkali metals, alkaline earth metals and lanthanide Storage material, comprising the Steps of: metals. (a) providing a precursor Solution comprising at least a 94. A method as recited claim 90, wherein said NO first precursor to a hydrogen Storage compound; absorbent compound comprises an oxide, hydroxide or carbonate of a metal selected from Na, K, Ca or Ba. (b) atomizing said precursor Solution to form precursor 95. A method as recited claim 90, wherein said NO droplets, and absorbent compound comprises MnO:ZrO. (c) heating Said precursor droplets to form dried precursor 96. A method as recited claim 90, wherein said NO droplets; absorbent compound comprises CeO2. and 97. A method as recited claim 90, wherein said NO absorbent compound comprises a Y-Ba-Cu-O com (d) converting said dried precursor droplets to an absor pound. bent material comprising an absorbent compound. 104. An absorbent material as recited in claim 103, 98. A method for the fabrication of a particulate HS wherein Said heating Step and Said converting Step occur absorbent material, comprising the Steps of: Sequentially in a Spray pyrolysis. (a) providing a precursor Solution comprising at least a 105. An absorbent material as recited in claim 103, first precursor to a H2S absorbent compound; wherein Said heating Step forms an intermediate compound capable of being post-processed to form a particulate absor (b) atomizing said precursor Solution to form precursor bent material, and wherein Said converting Step comprises droplets, and heating Said intermediate compound to form Said particulate (c) heating said precursor droplets to form a particulate absorbent material. NO, absorbent compound. 106. A method as recited in claim 103, wherein said hydrogen Storage compound comprises a misch metal. (d) converting said dried precursor droplets to an absor 107. A method as recited in claim 103, wherein said bent material comprising an absorbent compound. hydrogen Storage compound comprises a misch metal 99. An absorbent material as recited in claim 98, wherein Said heating Step and Said converting Step occur Sequentially Selected from the group consisting of LaNis, Mg-Ni, Mg2Fe, in a spray pyrolysis. TiFe, and ZrMn. 100. An absorbent material as recited in claim 98, wherein 108. A method as recited in claim 103, wherein said Said heating Step forms an intermediate compound capable hydrogen Storage compound comprises a metal hydride. of being post-processed to form a particulate absorbent 109. A method as recited in claim 103, wherein said material, and wherein Said converting Step comprises heat hydrogen Storage compound comprises a metal hydride ing Said intermediate compound to form Said particulate Selected from the group consisting of NaBH, AlH, LiAlH absorbent material. and Mg(AlH4). 101. A method as recited in claim 98, wherein said H.S 110. A method as recited in claim 103, wherein said absorbent compound comprises CaO. hydrogen Storage compound comprises an alkali metal 102. A method as recited in claim 98, wherein said H.S nitride. absorbent compound comprises ZnO.